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.
Published: 2026-07-16
Score: 5.5 Medium
EPSS: 1.4% Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

Prior to version 7.6, Squid’s cache digest reply handling suffered from an improper input validation bug (peerDigestSwapInMask in src/peer_digest.cc). This bug causes a heap‑based buffer overflow when a trusted peer sends a maliciously crafted cache_digest reply message: the cache digest’s on‑the‑wire size may exceed the mask_size declared within the digest. The flaw can be exercised only when Squid is compiled with the --enable-cache-digests option, and it leads to a crash of the Squid process, resulting in denial of service. The vulnerability is identified as CWE‑122 and CWE‑20.

Affected Systems

Squid caching proxy server versions prior to 7.6 that are compiled with the --enable-cache-digests option and configured with cache_peer entries are vulnerable. Any installation running an unpatched version that processes cache_digest replies can be exposed.

Risk and Exploitability

The CVSS score of 5.5 indicates moderate severity. The EPSS score of 1% suggests a low but nonzero probability of exploitation, and the issue is not listed in the CISA KEV catalog, which also indicates limited evidence of exploitation in the wild. The attacker must be a trusted server within the network, able to send crafted cache_digest replies to the vulnerable Squid instance. Successful exploitation would be internal or hybrid, causing a service disruption of the proxy.

Generated by OpenCVE AI on July 31, 2026 at 01:44 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade to the latest Squid release, which patches the cache_digest input validation flaw.
  • If an immediate patch is unavailable, disable the cache_digest feature or configure Squid to reject cache digest replies from untrusted sources.
  • Segregate or restrict network traffic so that only authorized servers can communicate with Squid, and employ ACLs or firewall rules to limit the scope of trust.

Generated by OpenCVE AI on July 31, 2026 at 01:44 UTC.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Debian DLA Debian DLA DLA-4697-1 squid security update
Debian DSA Debian DSA DSA-6360-1 squid security update
History

Fri, 17 Jul 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Thu, 16 Jul 2026 16:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in Squid. Due to improper input validation, a heap-based buffer overflow can occur when processing cache digests. This issue allows a trusted server to cause a denial of service when sending specially crafted replies to cache_digest request messages. 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.
Title squid: memory corruption in cache_digest reply handling Squid: Memory corruption in cache_digest reply handling
Weaknesses CWE-20
References

Fri, 26 Jun 2026 05:30:00 +0000

Type Values Removed Values Added
First Time appeared Squid-cache
Squid-cache squid
Vendors & Products Squid-cache
Squid-cache squid

Fri, 26 Jun 2026 00:15:00 +0000

Type Values Removed Values Added
Description A flaw was found in Squid. Due to improper input validation, a heap-based buffer overflow can occur when processing cache digests. This issue allows a trusted server to cause a denial of service when sending specially crafted replies to cache_digest request messages.
Title squid: memory corruption in cache_digest reply handling
Weaknesses CWE-122
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H'}

threat_severity

Moderate

Subscriptions

Squid-cache Squid
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-17T14:04:25.895Z

Reserved: 2026-06-02T22:46:02.579Z

Link: CVE-2026-50012

cve-icon Vulnrichment

Updated: 2026-07-17T14:04:22.831Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-06-23T00:00:00Z

Links: CVE-2026-50012 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-31T01:45:06Z

Weaknesses
  • CWE-122

    Heap-based Buffer Overflow

  • CWE-20

    Improper Input Validation