Description
Squid is a caching proxy for the Web. Due to an Uncontrolled Recursion bug in versions 2.6 through 2.7.STABLE9, versions 3.1 through 5.9, and versions 6.0.1 through 6.5, Squid may be vulnerable to a Denial of Service attack against HTTP Request parsing. This problem allows a remote client to perform Denial of Service attack by sending a large X-Forwarded-For header when the follow_x_forwarded_for feature is configured. This bug is fixed by Squid version 6.6. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| squid-cache | squid | >= 2.6, <= 2.7.STABLE9, >= 3.1, <= 5.9, >= 6.0.1, < 6.6 | — |
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 | 6.6-1 | — |
| Debian 13 | squid | 6.6-1 | — |
| Debian 12 | squid | 5.7-2+deb12u1 | DSA-5637-1 |
| Debian 11 | squid | 4.13-10+deb11u3 | DSA-5637-1 |
| Debian 10 | squid | 4.6-1+deb10u9 | DLA-3709-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | squid | 6.5-1ubuntu3 | — |
| Ubuntu 22.04 LTS | squid | 5.7-0ubuntu0.22.04.3 | USN-6594-1 |
| Ubuntu 20.04 LTS | squid | 4.10-1ubuntu1.9 | USN-6594-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | squid3 | 3.5.27-1ubuntu1.14+esm2 | USN-6857-1 |
| Ubuntu Pro 16.04 LTS | squid3 | 3.5.12-1ubuntu7.16+esm3 | USN-6857-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9 | squid | 7:5.5-6.el9_3.8 | RHSA-2024:1376 |
| RHEL 8 | libecap +1 | 1.0.1-2.module+el8.9.0+19703+a1da7223 | RHSA-2024:1375 |
| RHEL 8 | squid | 7:4.15-7.module+el8.9.0+21530+59b09a5b.10 | RHSA-2024:1375 |
| RHEL 7 | squid +2 | 7:3.5.20-17.el7_9.10 | RHSA-2024:1787 |
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_2.4 | RHSA-2024:1085 |
| 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_3.8 | ALSA-2024:1376 |
| AlmaLinux 8 | libecap +1 | 1.0.1-2.module_el8.6.0+2741+01592ae8 | ALSA-2024:1375 |
| AlmaLinux 8 | squid | 7:4.15-7.module_el8.9.0+3749+dbf371ed.10 | ALSA-2024:1375 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | libecap | 1.0.1-2.module+el8.9.0+1437+df5ea8f0 | RLSA-2024:1375 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP5 | squid | 5.7-150400.3.23.1 | SUSE-SU-2024:0455-1 |
| SLES 15 SP4 | squid | 5.7-150400.3.23.1 | SUSE-SU-2024:0455-1 |
| SLES 15 SP3 | squid | 4.17-150000.5.49.1 | SUSE-SU-2024:0298-1 |
| SLES 15 SP2 | squid | 4.17-150000.5.49.1 | SUSE-SU-2024:0298-1 |
| SLES 12 SP5 | squid | 4.17-4.41.1 | SUSE-SU-2024:0296-1 |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 SP4 | squid | 5.7-150400.3.23.1 | SUSE-SU-2024:0455-1 |
| SLES for SAP 15 SP3 | squid | 4.17-150000.5.49.1 | SUSE-SU-2024:0298-1 |
| SLES for SAP 15 SP2 | squid | 4.17-150000.5.49.1 | SUSE-SU-2024:0298-1 |
| SLES for SAP 12 SP5 | squid | 4.17-4.41.1 | SUSE-SU-2024:0296-1 |
| SLE HPC 15 SP4 | squid | 5.7-150400.3.23.1 | SUSE-SU-2024:0455-1 |
| SLE HPC 15 SP3 | squid | 4.17-150000.5.49.1 | SUSE-SU-2024:0298-1 |
| SLE HPC 15 SP2 | squid | 4.17-150000.5.49.1 | SUSE-SU-2024:0298-1 |
| SUSE Manager Server 4.3 | squid | 5.7-150400.3.23.1 | SUSE-SU-2024:0455-1 |
| SUSE Manager Proxy 4.3 | squid | 5.7-150400.3.23.1 | SUSE-SU-2024:0455-1 |
| SUSE Enterprise Storage 7.1 | squid | 4.17-150000.5.49.1 | SUSE-SU-2024:0298-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | squid | 6.6-2.1 | openSUSE-SU-2024:13631-1 |
| openSUSE Leap 15.5 | squid | 5.7-150400.3.23.1 | SUSE-SU-2024:0455-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | squid | 6.6-r0 | — |
| Alpine v3.23 | squid | 6.6-r0 | — |
| Alpine v3.22 | squid | 6.6-r0 | — |
| Alpine v3.21 | squid | 6.6-r0 | — |
| Alpine v3.20 | squid | 6.6-r0 | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | squid | 6.6-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | squid | 7:5.8-1.amzn2023.0.4 | ALAS2023-2024-467 |
| Amazon Linux 2 | squid +2 | 7:3.5.20-17.amzn2.7.16 | ALAS2-2024-2445 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 2 (CBL-Mariner) | squid | No fix yet | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 9 | squid | 7:5.5-6.0.1.el9_3.8 | ELSA-2024-1376 |
| Oracle Linux 8 | libecap +1 | 1.0.1-2.module+el8.9.0+90083+f7556140 | ELSA-2024-1375 |
| Oracle Linux 8 | squid | 7:4.15-7.module+el8.9.0+90184+ff65e696.10 | ELSA-2024-1375 |
| Oracle Linux 7 | squid +2 | 7:3.5.20-17.0.1.el7_9.10 | ELSA-2024-1787 |
Advisories 26
- ALSA-2024:1376 Important: squid security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2024:1375 Important: squid:4 security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2024:1375 Red Hat Security Advisory: squid:4 security update Red Hat Security Advisories (RHSA) · Sep 9, 2026
- RHSA-2024:1376 Red Hat Security Advisory: squid security update Red Hat Security Advisories (RHSA) · Sep 9, 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-2024:1787 Red Hat Security Advisory: squid security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- USN-6857-1 squid3 vulnerabilities Ubuntu Security Notices (USN) · Jun 25, 2026
- RHSA-2024:1085 Red Hat Security Advisory: squid security update Red Hat Security Advisories (RHSA) · Mar 18, 2026
- DSA-5637-1 squid - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-3709-1 squid - security update Debian Security (DSA / DLA) · Mar 9, 2026
- USN-6594-1 squid vulnerabilities Ubuntu Security Notices (USN) · Feb 10, 2026
- SUSE-SU-2024:0296-1 Security update for squid SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2024:0298-1 Security update for squid SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2024:0455-1 Security update for squid SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:13631-1 squid-6.6-2.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2023-3150 Squid: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Nov 18, 2025
- RLSA-2024:1375 Important: squid:4 security update Rocky Linux Security Advisories · May 7, 2025
- ELSA-2024-1787 Important: squid security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Apr 11, 2024
- ELSA-2024-1375 Important: squid:4 security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Mar 21, 2024
- ELSA-2024-1376 Important: squid security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Mar 20, 2024
- ALAS2-2024-2445 Important: squid security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Feb 1, 2024
- ALAS2023-2024-467 Important: squid security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Jan 8, 2024
References
- https://github.com/squid-cache/squid/security/advisories/GHSA-wgq4-4cfg-c4x3
- http://www.squid-cache.org/Versions/v5/SQUID-2023_10.patch
- http://www.squid-cache.org/Versions/v6/SQUID-2023_10.patch
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MEV66D3PAAY6K7TWDT3WZBLCPLASFJDC/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/A5QASTMCUSUEW3UOMKHZJB3FTONWSRXS/
- https://lists.debian.org/debian-lts-announce/2024/01/msg00003.html
- https://security.netapp.com/advisory/ntap-20240119-0005/