CVE-2021-43529

criticalpriority · track · 39EPSS 0.005 · 40 %ileEUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.47% (40th) EPSS

CVSS 9.8 · critical

Is it mine?

13 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · nvd · redhat_csaf

EPSS · scored 2026-10-27

Thunderbird versions prior to 91.3.0 are vulnerable to the heap overflow described in CVE-2021-43527 when processing S/MIME messages. Thunderbird versions 91.3.0 and later will not call the vulnerable code when processing S/MIME messages that contain certificates with DER-encoded DSA or RSA-PSS signatures.

remediations

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

A vendor fix is available.

Fixedthunderbird-0:91.3.0-2.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-2021:4130
Fixedthunderbird-0:91.3.0-2.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-2021:4130
Fixedthunderbird-0:91.3.0-2.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-2021:4130
Fixedthunderbird-0:91.3.0-2.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-2021:4130
Fixedthunderbird-0:91.3.0-2.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-2021:4130
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4130
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4130
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4130
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4130
Fixedthunderbird-debugsource-0:91.3.0-2.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-2021:4130
Fixedthunderbird-debugsource-0:91.3.0-2.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-2021:4130
Fixedthunderbird-debugsource-0:91.3.0-2.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-2021:4130
Fixedthunderbird-debugsource-0:91.3.0-2.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-2021:4130
Fixedthunderbird-0:91.3.0-2.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-2021:4132
Fixedthunderbird-0:91.3.0-2.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-2021:4132
Fixedthunderbird-0:91.3.0-2.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-2021:4132
Fixedthunderbird-0:91.3.0-2.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-2021:4132
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4132
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4132
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4132
Fixedthunderbird-debugsource-0:91.3.0-2.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-2021:4132
Fixedthunderbird-debugsource-0:91.3.0-2.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-2021:4132
Fixedthunderbird-debugsource-0:91.3.0-2.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-2021:4132
Fixedthunderbird-0:91.3.0-2.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-2021:4133
Fixedthunderbird-0:91.3.0-2.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-2021:4133
Fixedthunderbird-0:91.3.0-2.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-2021:4133
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4133
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4133
Fixedthunderbird-debugsource-0:91.3.0-2.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-2021:4133
Fixedthunderbird-debugsource-0:91.3.0-2.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-2021:4133
Fixedthunderbird-0:91.3.0-2.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-2021:4134
Fixedthunderbird-0:91.3.0-2.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-2021:4134
Fixedthunderbird-0:91.3.0-2.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-2021:4134
Fixedthunderbird-0:91.3.0-2.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-2021:4134
Fixedthunderbird-0:91.3.0-2.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-2021:4134
Fixedthunderbird-0:91.3.0-2.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-2021:4134
Fixedthunderbird-0:91.3.0-2.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-2021:4134
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4134
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4134
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4134
Fixedthunderbird-debuginfo-0:91.3.0-2.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-2021:4134

cvss

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

9.8

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 5.9

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · ENISA EU

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondaryexploitability 3.9 · impact 5.9

v3.19criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · Red Hat Product Security US

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-787USprimaryCWE-120US

affected products (13)

Products and version ranges known to be affected.

Mozilla Thunderbirdunspecified → 91.3.0enisa_euvdEU
mozilla thunderbird< 91.3.0nvdUScpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
thunderbird-0:91.3.0-2.el7_9.ppc64le as a component of Red Hat Enterprise Linux Server Optional (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.3.0-2.el7_9.src as a component of Red Hat Enterprise Linux Client (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.3.0-2.el7_9.src as a component of Red Hat Enterprise Linux Server Optional (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.3.0-2.el7_9.src as a component of Red Hat Enterprise Linux Workstation (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.3.0-2.el7_9.x86_64 as a component of Red Hat Enterprise Linux Client (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.3.0-2.el7_9.x86_64 as a component of Red Hat Enterprise Linux Server Optional (v. 7)all versionsfixedredhat_csafUS
thunderbird-0:91.3.0-2.el7_9.x86_64 as a component of Red Hat Enterprise Linux Workstation (v. 7)all versionsfixedredhat_csafUS
thunderbird-debuginfo-0:91.3.0-2.el7_9.ppc64le as a component of Red Hat Enterprise Linux Server Optional (v. 7)all versionsfixedredhat_csafUS
thunderbird-debuginfo-0:91.3.0-2.el7_9.x86_64 as a component of Red Hat Enterprise Linux Client (v. 7)all versionsfixedredhat_csafUS
thunderbird-debuginfo-0:91.3.0-2.el7_9.x86_64 as a component of Red Hat Enterprise Linux Server Optional (v. 7)all versionsfixedredhat_csafUS
thunderbird-debuginfo-0:91.3.0-2.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-2021:4130Red Hat Security Advisory: thunderbird security update2021-11-04csaf · 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-2021:4132Red Hat Security Advisory: thunderbird security update2021-11-04csaf · 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-2021:4133Red Hat Security Advisory: thunderbird security update2021-11-04csaf · 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-2021:4134Red Hat Security Advisory: thunderbird security update2021-11-04csaf · 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 2023-02-16modified 2026-06-17

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references (7)

External citations — patches, advisories, analysis.

scry

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