Squid Improper Input Validation Vulnerability - CVE-2026-50012

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 digest39s 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.