Description
Squid is a caching proxy for the Web. In versions 6.3 and below, Squid is vulnerable to a heap buffer overflow and possible remote code execution attack when processing URN due to incorrect buffer management. This has been fixed in version 6.4. To work around this issue, disable URN access permissions.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| squid-cache | squid | < 6.4 | — |
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 22.04 LTS | squid | 5.7-0ubuntu0.22.04.4 | — |
| Ubuntu 20.04 LTS | squid | 4.10-1ubuntu1.12 | — |
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 11 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 |
| RHEL 7 ELS | squid +2 | 7:3.5.20-17.el7_9.14 | RHSA-2025:14414 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| 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 |
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 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 7 | squid +2 | 7:3.5.20-17.0.7.el7_9.13 | ELSA-2025-14414 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 2 repositories
-
starrynightsecurity/CVE-2025-54574-Squid-Heap-Buffer-Overflow ★ 0 · Nov 17, 2025
Vulnerability Found on Squid Proxy.
-
gmh5225/Blackash-CVE-2025-54574 ★ 0 · Aug 5, 2025
CVE-2025-54574
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 16
- ALSA-2023:7668 Important: squid:4 security update AlmaLinux Security Advisories · Nov 6, 2026
- RHSA-2025:14414 Red Hat Security Advisory: squid security update Red Hat Security Advisories (RHSA) · Jul 12, 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
- WID-SEC-2025-1696 Squid: Schwachstelle ermöglicht Codeausführung BSI CERT-Bund (WID) · May 19, 2026
- DSA-5982-1 squid - security update Debian Security (DSA / DLA) · Mar 9, 2026
- ELSA-2025-14414 Important: squid security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Sep 29, 2025
- 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
- ELSA-2023-7465 Important: squid security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Nov 28, 2023