Description
Squid is a caching proxy for the Web. Prior to 7.6, due to an improper input validation bug in cache digest reply handling (peerDigestSwapInMask in src/peer_digest.cc), Squid is vulnerable to a heap-based buffer overflow: a cache digest's on-the-wire size may be larger than the mask_size declared within the digest, so a trusted peer sending a maliciously crafted reply to a cache_digest request message can trigger the overflow. This attack is limited to Squid instances compiled with the --enable-cache-digests option and configured with cache_peer entries. This issue is fixed in version 7.6.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| squid-cache | squid | < 7.6 | — |
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 | 7.6-1 | — |
| Debian 13 | squid | 6.13-2+deb13u2 | — |
| Debian 12 | squid | 5.7-2+deb12u6 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | squid | 7.2-2ubuntu2.2 | — |
| Ubuntu 25.10 | squid | 6.14-0ubuntu0.25.10.4 | — |
| Ubuntu 24.04 LTS | squid | 6.14-0ubuntu0.24.04.4 | USN-8941-1 |
| Ubuntu 22.04 LTS | squid | 5.9-0ubuntu0.22.04.7 | USN-8941-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | squid | 4.10-1ubuntu1.13+esm3 | USN-8941-1 |
| Ubuntu Pro 18.04 LTS | squid3 | 3.5.27-1ubuntu1.14+esm6 | USN-8941-1 |
| Ubuntu Pro 16.04 LTS | squid3 | 3.5.12-1ubuntu7.16+esm7 | USN-8941-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | squid | 6.14-150600.3.20.1 | SUSE-SU-2026:4621-1 |
| SLES 15 SP6 | squid | 6.14-150600.3.20.1 | SUSE-SU-2026:4621-1 |
| 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 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | squid | 6.14-160000.1.1 | SUSE-SU-2026:24224-1 |
| SLES for SAP 15 SP6 | squid | 6.14-150600.3.20.1 | SUSE-SU-2026:4621-1 |
| 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 |
| SLES 16.0 | squid | 6.14-160000.1.1 | SUSE-SU-2026:24224-1 |
| 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 | 7.7-2.1 | openSUSE-SU-2026:11937-1 |
| openSUSE Leap 16.0 | squid | 6.14-160000.1.1 | openSUSE-SU-2026:22080-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | squid | 7.6-r0 | — |
| Alpine v3.23 | squid | 7.6-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | squid | 7:6.13-1.amzn2023.0.5 | ALAS2023-2026-1858 |
| Amazon Linux 2 | squid +2 | 7:3.5.20-17.amzn2.7.27 | ALAS2-2026-3371 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | squid | 6.13-5 | — |
Advisories 9
- WID-SEC-2026-1920 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
- USN-8941-1 squid, squid3 vulnerabilities Ubuntu Security Notices (USN) · Oct 21, 2026
- SUSE-SU-2026:24224-1 Security update for squid SUSE / openSUSE Security Updates · Oct 21, 2026
- openSUSE-SU-2026:22080-1 Security update for squid SUSE / openSUSE Security Updates · Oct 19, 2026
- SUSE-SU-2026:4621-1 Security update for squid SUSE / openSUSE Security Updates · Oct 13, 2026
- openSUSE-SU-2026:11937-1 squid-7.7-2.1 on GA media SUSE / openSUSE Security Updates · Oct 1, 2026
- ALAS2-2026-3371 Important: squid security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Jun 22, 2026
- ALAS2023-2026-1858 Important: squid security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Jun 22, 2026