What’s Vulnerable › Vulnerabilities

CVE-2020-24606

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 5.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-08-24 · updated 2026-06-17
• Weakness: CWE-667

Description

Squid before 4.13 and 5.x before 5.0.4 allows a trusted peer to perform Denial of Service by consuming all available CPU cycles during handling of a crafted Cache Digest response message. This only occurs when cache_peer is used with the cache digests feature. The problem exists because peerDigestHandleReply() livelocking in peer_digest.cc mishandles EOF.

Affected products

• Canonical Ubuntu Linux: 16.04, 18.04, 20.04
• Debian Linux: 9.0, 10.0
• Fedoraproject Fedora: 31, 32, 33
• openSUSE Leap: 15.1, 15.2
• Squid: from 3.0 before 4.13; from 5.0.1 before 5.0.4 — fixed in 4.13, 5.0.4

How to fix

Upgrade to a fixed version: Squid 4.13, 5.0.4. Check the vendor advisory for mitigations.

References

• http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00012.html
• http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00017.html
• http://www.squid-cache.org/Versions/v4/changesets/SQUID-2020_9.patch
• https://github.com/squid-cache/squid/security/advisories/GHSA-vvj7-xjgq-g2jg
• https://lists.debian.org/debian-lts-announce/2020/10/msg00005.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BE6FKUN7IGTIR2MEEMWYDT7N5EJJLZI2/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BMTFLVB7GLRF2CKGFPZ4G4R5DIIPHWI3/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HJJDI7JQFGQLVNCKMVY64LAFMKERAOK7/
• https://security.netapp.com/advisory/ntap-20210219-0007/
• https://security.netapp.com/advisory/ntap-20210226-0006/
• https://security.netapp.com/advisory/ntap-20210226-0007/
• https://usn.ubuntu.com/4477-1/

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