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.
Fix
Patch, vendor advisory and mitigation references on NVD 3
- https://github.com/squid-cache/squid/commit/19fcfe922717c8b255270c032dcde4071c003bcd Patch
- https://github.com/squid-cache/squid/pull/2423 Patch
- https://github.com/squid-cache/squid/security/advisories/GHSA-5vmx-9x64-9284 Vendor Advisory
Vendor advisories in the News 1
- USN-8941-1: Squid vulnerabilities Ubuntu Security Notices · 2026-10-20
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 5.5 · squid-cacheNVD modified 2026-10-24 20:10
Affected (CPE criteria) 1
cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
References 4
- https://github.com/squid-cache/squid/commit/19fcfe922717c8b255270c032dcde4071c003bcd Patch
- https://github.com/squid-cache/squid/pull/2423 Patch
- https://github.com/squid-cache/squid/releases/tag/SQUID_7_6 Release Notes
- https://github.com/squid-cache/squid/security/advisories/GHSA-5vmx-9x64-9284 Vendor Advisory