CVE-2021-38502

mediumpriority · track · 24OT risk · elevatedEPSS 0.011 · 66 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.10% (66th) EPSS

CVSS 4.3 · medium

Is it mine?

16 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · nvd · redhat_csaf

EPSS · scored 2026-10-28

Thunderbird ignored the configuration to require STARTTLS security for an SMTP connection. A MITM could perform a downgrade attack to intercept transmitted messages, or could take control of the authenticated session to execute SMTP commands chosen by the MITM. If an unprotected authentication method was configured, the MITM could obtain the authentication credentials, too. This vulnerability affects Thunderbird < 91.2.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

Fixedthunderbird-0:91.2.0-1.el8_4.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-0:91.2.0-1.el8_4.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-0:91.2.0-1.el8_4.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-0:91.2.0-1.el8_4.src as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-0:91.2.0-1.el8_4.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-debuginfo-0:91.2.0-1.el8_4.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-debuginfo-0:91.2.0-1.el8_4.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-debuginfo-0:91.2.0-1.el8_4.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-debuginfo-0:91.2.0-1.el8_4.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-debugsource-0:91.2.0-1.el8_4.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-debugsource-0:91.2.0-1.el8_4.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-debugsource-0:91.2.0-1.el8_4.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-debugsource-0:91.2.0-1.el8_4.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3838
Fixedthunderbird-0:91.2.0-1.el8_2.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.2)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3839
Fixedthunderbird-0:91.2.0-1.el8_2.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.2)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3839
Fixedthunderbird-0:91.2.0-1.el8_2.src as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.2)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3839
Fixedthunderbird-0:91.2.0-1.el8_2.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.2)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3839
Fixedthunderbird-debuginfo-0:91.2.0-1.el8_2.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.2)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3839
Fixedthunderbird-debuginfo-0:91.2.0-1.el8_2.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.2)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3839
Fixedthunderbird-debuginfo-0:91.2.0-1.el8_2.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.2)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3839
Fixedthunderbird-debugsource-0:91.2.0-1.el8_2.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.2)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3839
Fixedthunderbird-debugsource-0:91.2.0-1.el8_2.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.2)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3839
Fixedthunderbird-debugsource-0:91.2.0-1.el8_2.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.2)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3839
Fixedthunderbird-0:91.2.0-1.el8_1.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3840
Fixedthunderbird-0:91.2.0-1.el8_1.src as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3840
Fixedthunderbird-0:91.2.0-1.el8_1.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3840
Fixedthunderbird-debuginfo-0:91.2.0-1.el8_1.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3840
Fixedthunderbird-debuginfo-0:91.2.0-1.el8_1.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3840
Fixedthunderbird-debugsource-0:91.2.0-1.el8_1.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3840
Fixedthunderbird-debugsource-0:91.2.0-1.el8_1.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3840
Fixedthunderbird-0:91.2.0-1.el7_9.ppc64le as a component of Red Hat Enterprise Linux Server Optional (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841
Fixedthunderbird-0:91.2.0-1.el7_9.src as a component of Red Hat Enterprise Linux Client (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841
Fixedthunderbird-0:91.2.0-1.el7_9.src as a component of Red Hat Enterprise Linux Server Optional (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841
Fixedthunderbird-0:91.2.0-1.el7_9.src as a component of Red Hat Enterprise Linux Workstation (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841
Fixedthunderbird-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Client (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841
Fixedthunderbird-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Server Optional (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841
Fixedthunderbird-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Workstation (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841
Fixedthunderbird-debuginfo-0:91.2.0-1.el7_9.ppc64le as a component of Red Hat Enterprise Linux Server Optional (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841
Fixedthunderbird-debuginfo-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Client (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841
Fixedthunderbird-debuginfo-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Server Optional (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841
Fixedthunderbird-debuginfo-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Workstation (v. 7)redhat_csaf
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
https://access.redhat.com/errata/RHSA-2021:3841

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.3–7.5

v2.04.3mediumAV:N/AC:M/Au:N/C:P/I:N/A:Nprimary · NVD / NIST USexploitability 8.6 · impact 2.9

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:Nprimary · NVD / NIST USexploitability 2.2 · impact 3.6

v3.07.5highCVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · Red Hat Product Security US

v3.15.4mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-319US

affected products (16)

Products and version ranges known to be affected.

Mozilla Thunderbirdunspecified → 91.2enisa_euvdEU
debian debian linux= 10.0nvdUScpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*
debian debian linux= 11.0nvdUScpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*
debian debian linux= 9.0nvdUScpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*
mozilla thunderbird< 91.2nvdUScpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
thunderbird-0:91.2.0-1.el7_9.ppc64le as a component of Red Hat Enterprise Linux Server Optional (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.2.0-1.el7_9.src as a component of Red Hat Enterprise Linux Client (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.2.0-1.el7_9.src as a component of Red Hat Enterprise Linux Server Optional (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.2.0-1.el7_9.src as a component of Red Hat Enterprise Linux Workstation (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Client (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Server Optional (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Workstation (v. 7)all versionsfixedredhat_csafUS
thunderbird-debuginfo-0:91.2.0-1.el7_9.ppc64le as a component of Red Hat Enterprise Linux Server Optional (v. 7)all versionsfixedredhat_csafUS
thunderbird-debuginfo-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Client (v. 7)all versionsfixedredhat_csafUS
thunderbird-debuginfo-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Server Optional (v. 7)all versionsfixedredhat_csafUS
thunderbird-debuginfo-0:91.2.0-1.el7_9.x86_64 as a component of Red Hat Enterprise Linux Workstation (v. 7)all versionsfixedredhat_csafUS

advisories (4)

Vendor and ecosystem advisories describing this.

RHSA-2021:3838Red Hat Security Advisory: thunderbird security update2021-10-13csaf · redhat_csafUS
An update for thunderbird is now available for Red Hat Enterprise Linux 8. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.
RHSA-2021:3839Red Hat Security Advisory: thunderbird security update2021-10-13csaf · redhat_csafUS
An update for thunderbird is now available for Red Hat Enterprise Linux 8.2 Extended Update Support. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.
RHSA-2021:3840Red Hat Security Advisory: thunderbird security update2021-10-13csaf · redhat_csafUS
An update for thunderbird is now available for Red Hat Enterprise Linux 8.1 Extended Update Support. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.
RHSA-2021:3841Red Hat Security Advisory: thunderbird security update2021-10-13csaf · redhat_csafUS
An update for thunderbird is now available for Red Hat Enterprise Linux 7. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd redhat_csaf NVD CVE.org MITRE

published 2021-11-03modified 2026-06-17

references (24)

External citations — patches, advisories, analysis.

scry

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