CVE-2026-50012: Squid: Memory corruption in cache_digest reply handling
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/peerdigest.cc), Squid is vulnerable to a heap-based buffer overflow: a cache digest's on-the-wire size may be larger than the masksize declared within the digest, so a trusted peer sending a maliciously crafted reply to a cachedigest request message can trigger the overflow. This attack is limited to Squid instances compiled with the --enable-cache-digests option and configured with cachepeer entries. This issue is fixed in version 7.6.
Other sources
Squid: Memory corruption in cachedigest reply handling
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.13-5 - Upgrade
Upgrade
squidto a version that resolves this vulnerability.Fixed in 7.6 - Compensating control
If you cannot upgrade immediately, limit or remove trust for cache peers configured with cache_peer entries, because exploitation requires Squid instances that are compiled with --enable-cache-digests and configured with cache_peer.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-50012?
The severity of CVE-2026-50012 is classified as high due to its potential to allow unauthorized access.
How do I fix CVE-2026-50012?
To mitigate CVE-2026-50012, update your Squid installation to the latest version that includes the security patch.
What systems are affected by CVE-2026-50012?
CVE-2026-50012 affects all versions of Squid prior to the patched release.
What types of attacks can exploit CVE-2026-50012?
CVE-2026-50012 can be exploited to launch unauthorized actions against the Squid server due to improper access controls.
Is there a workaround for CVE-2026-50012 if I cannot update?
As a temporary workaround for CVE-2026-50012, you can restrict access by modifying the Squid configuration to limit user permissions.