CVE-2026-50012: squid-cache squid Improper Input Validation

Vulnerability summary

CVE-2026-50012 is a medium (CVSS 5.5) Improper Input Validation vulnerability in squid-cache squid. EPSS estimates a 1.36% chance of exploitation in the next 30 days, higher than 71.3% of scored vulnerabilities.

Timeline

1. 16-07-2026
   PublishedVulnerability first disclosed.
2. 17-07-2026
   Last modifiedVulnerability information updated.

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.

• CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
• CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().