CVE-2020-25097

Severity: high (CVSS 8.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 7.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-03-19 · updated 2026-06-17
Weakness: CWE-20

Description

An issue was discovered in Squid through 4.13 and 5.x through 5.0.4. Due to improper input validation, it allows a trusted client to perform HTTP Request Smuggling and access services otherwise forbidden by the security controls. This occurs for certain uri_whitespace configuration settings.

Affected products

Debian Linux: 10.0
Fedoraproject Fedora: 32, 33, 34
Cloud Manager: all versions
Squid: from 2.0 before 4.14; from 5.0.1 before 5.0.5 — fixed in 4.14, 5.0.5

How to fix

Upgrade to a fixed version: Squid 4.14, 5.0.5. Check the vendor advisory for mitigations.

References

http://www.squid-cache.org/Versions/v4/changesets/SQUID-2020_11.patch
http://www.squid-cache.org/Versions/v5/changesets/SQUID-2020_11.patch
https://github.com/squid-cache/squid/security/advisories/GHSA-jvf6-h9gj-pmj6
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DJMDRVV677AJL4BZAOLCT5LMFCGBZTC2/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FBXFWKIGXPERDVQXG556LLPUOCMQGERC/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/O3RYBDMJCPYGOSURWDR3WJTE474UFT77/
https://security.gentoo.org/glsa/202105-14
https://security.netapp.com/advisory/ntap-20210727-0010/
https://www.debian.org/security/2021/dsa-4873
http://www.squid-cache.org/Versions/v4/changesets/SQUID-2020_11.patch
http://www.squid-cache.org/Versions/v5/changesets/SQUID-2020_11.patch
https://github.com/squid-cache/squid/security/advisories/GHSA-jvf6-h9gj-pmj6

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