CVE-2021-28116

mediumpriority · track · 26EPSS 0.129 · 96 %ileDEEURUUS

grimoire priorityP1 · Urgent

Exploitable?

—

no known exploitation

Likely / severe?

12.9% (96th) EPSS

CVSS 4.3 · medium

Is it mine?

53 products

Check your exposure

Who says so?

6 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

Squid through 4.14 and 5.x through 5.0.5, in some configurations, allows information disclosure because of an out-of-bounds read in WCCP protocol data. This can be leveraged as part of a chain for remote code execution as nobody.

remediations

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

A vendor fix is available.

Fixedlibecap-0:1.0.1-2.module+el8.1.0+4044+36416a77.aarch64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-0:1.0.1-2.module+el8.1.0+4044+36416a77.ppc64le (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-0:1.0.1-2.module+el8.1.0+4044+36416a77.s390x (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-0:1.0.1-2.module+el8.1.0+4044+36416a77.src (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-0:1.0.1-2.module+el8.1.0+4044+36416a77.x86_64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-debuginfo-0:1.0.1-2.module+el8.1.0+4044+36416a77.aarch64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-debuginfo-0:1.0.1-2.module+el8.1.0+4044+36416a77.ppc64le (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-debuginfo-0:1.0.1-2.module+el8.1.0+4044+36416a77.s390x (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-debuginfo-0:1.0.1-2.module+el8.1.0+4044+36416a77.x86_64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-debugsource-0:1.0.1-2.module+el8.1.0+4044+36416a77.aarch64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-debugsource-0:1.0.1-2.module+el8.1.0+4044+36416a77.ppc64le (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-debugsource-0:1.0.1-2.module+el8.1.0+4044+36416a77.s390x (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-debugsource-0:1.0.1-2.module+el8.1.0+4044+36416a77.x86_64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-devel-0:1.0.1-2.module+el8.1.0+4044+36416a77.aarch64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-devel-0:1.0.1-2.module+el8.1.0+4044+36416a77.ppc64le (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-devel-0:1.0.1-2.module+el8.1.0+4044+36416a77.s390x (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedlibecap-devel-0:1.0.1-2.module+el8.1.0+4044+36416a77.x86_64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-7:4.15-3.module+el8.6.0+14176+9782b8ab.aarch64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-7:4.15-3.module+el8.6.0+14176+9782b8ab.ppc64le (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-7:4.15-3.module+el8.6.0+14176+9782b8ab.s390x (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-7:4.15-3.module+el8.6.0+14176+9782b8ab.src (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-7:4.15-3.module+el8.6.0+14176+9782b8ab.x86_64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-debuginfo-7:4.15-3.module+el8.6.0+14176+9782b8ab.aarch64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-debuginfo-7:4.15-3.module+el8.6.0+14176+9782b8ab.ppc64le (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-debuginfo-7:4.15-3.module+el8.6.0+14176+9782b8ab.s390x (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-debuginfo-7:4.15-3.module+el8.6.0+14176+9782b8ab.x86_64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-debugsource-7:4.15-3.module+el8.6.0+14176+9782b8ab.aarch64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-debugsource-7:4.15-3.module+el8.6.0+14176+9782b8ab.ppc64le (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-debugsource-7:4.15-3.module+el8.6.0+14176+9782b8ab.s390x (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939
Fixedsquid-debugsource-7:4.15-3.module+el8.6.0+14176+9782b8ab.x86_64 (squid:4) 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 After installing this update, the squid service will be restarted automatically.
https://access.redhat.com/errata/RHSA-2022:1939

cvss

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

6.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 3.7–6.5

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

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:Nprimary · NVD / NIST USexploitability 3.9 · impact 1.4

v3.16.5mediumAV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:Nsecondary · FSTEC (BDU) RU

v3.13.7lowCVSS:3.1/AC:H/AV:N/A:N/C:L/I:N/PR:N/S:U/UI:Nsecondary · ENISA EU

v3.13.7lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:Nsecondary · cve@mitre.org USexploitability 2.2 · impact 1.4

v3.14.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:Nsecondary · Red Hat Product Security US

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-125USprimaryCWE-125USCWE-125US

affected products (53)

Products and version ranges known to be affected.

Amazon Linux 2all versionscert_bundDEcpe:/o:amazon:linux_2:-
Debian Linuxall versionscert_bundDEcpe:/o:debian:debian_linux:-
Gentoo Linuxall versionscert_bundDEcpe:/o:gentoo:linux:-
Open Source Squid <= 4.14all versionscert_bundDEcpe:/a:squid-cache:squid:4.14
Open Source Squid <= 5.0.5all versionscert_bundDEcpe:/a:squid-cache:squid:5.0.5
Oracle Linuxall versionscert_bundDEcpe:/o:oracle:linux:-
Red Hat Enterprise Linuxall versionscert_bundDEcpe:/o:redhat:enterprise_linux:-
SUSE Linuxall versionscert_bundDEcpe:/o:suse:suse_linux:-
Ubuntu Linuxall versionscert_bundDEcpe:/o:canonical:ubuntu_linux:-
n/a n/a≤ n/aenisa_euvdEU
Squid Software Foundation Squid≤ 5.2fstec_bduRU
АО «ИВК» Альт 8 СПall versionsfstec_bduRU
АО «НППКТ» ОСОН ОСнова Оnyx≤ 2.5fstec_bduRU
ООО «Ред Софт» РЕД ОС≤ 7.2 Муромfstec_bduRU
ООО «РусБИТех-Астра» Astra Linux Common Edition≤ 1.6 «Смоленск»fstec_bduRU
ООО «РусБИТех-Астра» Astra Linux Special Edition≤ 4.7fstec_bduRU
ООО «РусБИТех-Астра» Astra Linux Special Edition≤ 1.7fstec_bduRU
debian debian linux= 10.0nvdUScpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*
debian debian linux= 11.0nvdUScpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*
fedoraproject fedora= 33nvdUScpe:2.3:o:fedoraproject:fedora:*:*:*:*:*:*:*:*

showing 20 of 53

advisories (2)

Vendor and ecosystem advisories describing this.

RHSA-2022:1939Red Hat Security Advisory: squid:4 security and bug fix update2022-05-10csaf · redhat_csafUS
An update for the squid:4 module is now available for Red Hat Enterprise Linux 8. Red Hat Product Security has rated this update as having a security impact of Moderate. 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.
WID-SEC-W-2022-0481Squid: Schwachstelle ermöglicht Offenlegung von InformationenDeutsch2021-03-09csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Squid ausnutzen, um Informationen offenzulegen.

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund nvd redhat_csaf NVD CVE.org MITRE

published 2021-03-09modified 2026-06-17

related (11,874)

Related entries.

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+11869 more

references (38)

External citations — patches, advisories, analysis.

scry

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