Description
A flaw was found in Squid. The limits applied for validation of HTTP response headers are applied before caching. However, Squid may grow a cached HTTP response header beyond the configured maximum size, causing a stall or crash of the worker process when a large header is retrieved from the disk cache, resulting in a denial of service.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 8.2 Advanced Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 8.2 Telecommunications Update Service | — | — |
| Red Hat | Red Hat Enterprise Linux 8.2 Update Services for SAP Solutions | — | — |
| Red Hat | Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 8.4 Telecommunications Update Service | — | — |
| Red Hat | Red Hat Enterprise Linux 8.4 Update Services for SAP Solutions | — | — |
| Red Hat | Red Hat Enterprise Linux 8.6 Extended Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 8.8 Extended Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat Enterprise Linux 9.0 Extended Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 9.2 Extended Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | squid | 6.5-1 | — |
| Debian 13 | squid | 6.5-1 | — |
| Debian 12 | squid | 5.7-2+deb12u3 | DSA-5982-1 |
| Debian 11 | squid | 4.13-10+deb11u5 | DLA-4312-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | squid | 6.5-1ubuntu1 | — |
| Ubuntu 22.04 LTS | squid | 5.7-0ubuntu0.22.04.4 | USN-6728-1 |
| Ubuntu 20.04 LTS | squid | 4.10-1ubuntu1.12 | USN-6728-3, USN-6728-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | squid3 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | squid3 | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9 | squid | 7:5.5-6.el9_3.2 | RHSA-2023:7465 |
| RHEL 8 | libecap +1 | 1.0.1-2.module+el8.9.0+19703+a1da7223 | RHSA-2023:7668 |
| RHEL 8 | squid | 7:4.15-7.module+el8.9.0+20806+014d88aa.3 | RHSA-2023:7668 |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9.2 EUS | squid | 7:5.5-5.el9_2.3 | RHSA-2024:0072 |
| RHEL 9.0 EUS | squid | 7:5.2-1.el9_0.4 | RHSA-2024:1153 |
| RHEL 8.8 EUS | libecap +1 | 1.0.1-2.module+el8.1.0+4044+36416a77 | RHSA-2024:0397 |
| RHEL 8.8 EUS | squid | 7:4.15-6.module+el8.8.0+21068+0ecbc070.3 | RHSA-2024:0397 |
| RHEL 8.6 EUS | libecap +1 | 1.0.1-2.module+el8.1.0+4044+36416a77 | RHSA-2024:0771 |
| RHEL 8.6 EUS | squid | 7:4.15-3.module+el8.6.0+21069+a1561e3d.4 | RHSA-2024:0771 |
| RHEL 8.4 TUS | libecap +1 | 1.0.1-2.module+el8.1.0+4044+36416a77 | RHSA-2024:0773 |
| RHEL 8.4 TUS | squid | 7:4.11-4.module+el8.4.0+21174+3894a031.6 | RHSA-2024:0773 |
| RHEL 8.4 E4S | libecap +1 | 1.0.1-2.module+el8.1.0+4044+36416a77 | RHSA-2024:0773 |
| RHEL 8.4 E4S | squid | 7:4.11-4.module+el8.4.0+21174+3894a031.6 | RHSA-2024:0773 |
| RHEL 8.4 AUS | libecap +1 | 1.0.1-2.module+el8.1.0+4044+36416a77 | RHSA-2024:0773 |
| RHEL 8.4 AUS | squid | 7:4.11-4.module+el8.4.0+21174+3894a031.6 | RHSA-2024:0773 |
| RHEL 8.2 TUS | libecap +1 | 1.0.1-2.module+el8.1.0+4044+36416a77 | RHSA-2024:0772 |
| RHEL 8.2 TUS | squid | 7:4.4-8.module+el8.2.0+21173+22259b09.7 | RHSA-2024:0772 |
| RHEL 8.2 E4S | libecap +1 | 1.0.1-2.module+el8.1.0+4044+36416a77 | RHSA-2024:0772 |
| RHEL 8.2 E4S | squid | 7:4.4-8.module+el8.2.0+21173+22259b09.7 | RHSA-2024:0772 |
| RHEL 8.2 AUS | libecap +1 | 1.0.1-2.module+el8.1.0+4044+36416a77 | RHSA-2024:0772 |
| RHEL 8.2 AUS | squid | 7:4.4-8.module+el8.2.0+21173+22259b09.7 | RHSA-2024:0772 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 9 | squid | 7:5.5-6.el9_3.2 | ALSA-2023:7465 |
| AlmaLinux 8 | libecap +1 | 1.0.1-2.module_el8.6.0+2741+01592ae8 | ALSA-2023:7668 |
| AlmaLinux 8 | squid | 7:4.15-7.module_el8.9.0+3696+b881db49.3 | ALSA-2023:7668 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | libecap | 1.0.1-2.module+el8.9.0+1437+df5ea8f0 | RLSA-2023:7668 |
| Rocky Linux 8 | squid | 7:4.15-7.module+el8.9.0+1568+6d4fd5d4.1 | RLSA-2023:7668 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP5 | squid | 5.7-150400.3.41.1 | SUSE-SU-2026:4909-1 |
| SLES 15 SP4 | squid | 5.7-150400.3.41.1 | SUSE-SU-2026:4909-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 SP5 | squid | 5.7-150400.3.41.1 | SUSE-SU-2026:4909-1 |
| SLES for SAP 15 SP4 | squid | 5.7-150400.3.41.1 | SUSE-SU-2026:4909-1 |
| SLE HPC 15 SP5 | squid | 5.7-150400.3.41.1 | SUSE-SU-2026:4909-1 |
| SLE HPC 15 SP4 | squid | 5.7-150400.3.41.1 | SUSE-SU-2026:4909-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | squid | 6.4-1.1 | openSUSE-SU-2024:13398-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | squid | 7:6.6-1.amzn2023.0.3 | ALAS2023-2024-578 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | squid | 6.5-1 | — |
| Azure Linux 2 (CBL-Mariner) | squid | No fix yet | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 9 | squid | 7:5.5-6.el9_3.2 | ELSA-2023-7465 |
| Oracle Linux 8 | libecap +1 | 1.0.1-2.module+el8.9.0+90083+f7556140 | ELSA-2023-7668 |
| Oracle Linux 8 | squid | 7:4.15-7.module+el8.9.0+90100+fede0fa7.3 | ELSA-2023-7668 |
Advisories 22
- ALSA-2023:7668 Important: squid:4 security update AlmaLinux Security Advisories · Nov 6, 2026
- ALSA-2023:7465 Important: squid security update AlmaLinux Security Advisories · Oct 29, 2026
- WID-SEC-2023-2725 Squid: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 26, 2026
- SUSE-SU-2026:4909-1 Security update for squid SUSE / openSUSE Security Updates · Oct 26, 2026
- RHSA-2024:1153 Red Hat Security Advisory: squid security update Red Hat Security Advisories (RHSA) · Jul 12, 2026
- RHSA-2024:0772 Red Hat Security Advisory: squid:4 security update Red Hat Security Advisories (RHSA) · Jul 12, 2026
- RHSA-2024:0773 Red Hat Security Advisory: squid:4 security update Red Hat Security Advisories (RHSA) · Jul 12, 2026
- RHSA-2024:0771 Red Hat Security Advisory: squid:4 security update Red Hat Security Advisories (RHSA) · Jul 12, 2026
- RHSA-2024:0397 Red Hat Security Advisory: squid:4 security update Red Hat Security Advisories (RHSA) · Jul 12, 2026
- RHSA-2024:0072 Red Hat Security Advisory: squid security update Red Hat Security Advisories (RHSA) · Jul 12, 2026
- RHSA-2023:7668 Red Hat Security Advisory: squid:4 security update Red Hat Security Advisories (RHSA) · Jul 12, 2026
- RHSA-2023:7465 Red Hat Security Advisory: squid security update Red Hat Security Advisories (RHSA) · Jul 12, 2026
- USN-6728-1 squid vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- USN-6728-3 squid vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- DSA-5982-1 squid - security update Debian Security (DSA / DLA) · Mar 9, 2026
- RLSA-2023:7668 Important: squid:4 security update Rocky Linux Security Advisories · Feb 5, 2026
- openSUSE-SU-2024:13398-1 squid-6.4-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- DLA-4312-1 squid - security update Debian Security (DSA / DLA) · Sep 27, 2025
- ALAS2023-2024-578 Important: squid security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Aug 26, 2025
- WID-SEC-2024-1248 Xerox FreeFlow Print Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 21, 2024
- ELSA-2023-7668 Important: squid:4 security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Dec 11, 2023
- ELSA-2023-7465 Important: squid security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Nov 28, 2023
References
- RHSA-2023:7465 vendor-advisory
- RHSA-2023:7668 vendor-advisory
- RHSA-2024:0072 vendor-advisory
- RHSA-2024:0397 vendor-advisory
- RHSA-2024:0771 vendor-advisory
- RHSA-2024:0772 vendor-advisory
- RHSA-2024:0773 vendor-advisory
- RHSA-2024:1153 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2023-5824 vdb-entry
- RHBZ#2245914 issue-tracking
- https://github.com/squid-cache/squid/security/advisories/GHSA-543m-w2m2-g255