What’s Vulnerable › Vulnerabilities

CVE-2026-50012: Squid: Memory corruption in cache_digest reply handling

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-16 · updated 2026-10-24
• Weakness: CWE-20

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

• Squid: before 7.6 — fixed in 7.6

How to fix

Upgrade to a fixed version: Squid 7.6. Check the vendor advisory for mitigations.

References

• https://github.com/squid-cache/squid/commit/19fcfe922717c8b255270c032dcde4071c003bcd
• https://github.com/squid-cache/squid/pull/2423
• https://github.com/squid-cache/squid/releases/tag/SQUID_7_6
• https://github.com/squid-cache/squid/security/advisories/GHSA-5vmx-9x64-9284

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