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Vulnerability record · CVE-2021-31808 · published 27 May 2021

CVE-2021-31808: Squid-cache squid integer overflow vulnerability

Squid Cache · Squid

An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to an input-validation bug, it is vulnerable to a Denial of Service attack (against all clients using the proxy). A client sends an HTTP Range request to trigger this.

6.5 CVSS 3.1 Medium EPSS 5.3% · top 7.7% CWE-190 · Integer overflow
6.5CVSS 3.1 base score, v2 4.0
5.3%EPSS exploitation probability, 30 days
NoNot in CISA KEV
4Affected product versions listed by NVD
18References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to an input-validation bug, it is vulnerable to a Denial of Service attack (against all clients using the proxy). A client sends an HTTP Range request to trigger this.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

4 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://seclists.org/fulldisclosure/2023/Oct/14 Mailing ListThird Party Advisory
http://www.openwall.com/lists/oss-security/2023/10/11/3 Mailing ListThird Party Advisory
http://www.squid-cache.org/Versions/v4/changesets/squid-4-e7cf864f938f24eea8af0692c04d16790983c823.patch ExploitPatchVendor Advisory
https://github.com/squid-cache/squid/security/advisories/GHSA-pxwq-f3qr-w2xf PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00014.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2V
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBT
https://security.netapp.com/advisory/ntap-20210716-0007/ Third Party Advisory
https://www.debian.org/security/2021/dsa-4924 Third Party Advisory
http://seclists.org/fulldisclosure/2023/Oct/14 Mailing ListThird Party Advisory
http://www.openwall.com/lists/oss-security/2023/10/11/3 Mailing ListThird Party Advisory
http://www.squid-cache.org/Versions/v4/changesets/squid-4-e7cf864f938f24eea8af0692c04d16790983c823.patch ExploitPatchVendor Advisory
https://github.com/squid-cache/squid/security/advisories/GHSA-pxwq-f3qr-w2xf PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00014.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2V
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBT
https://security.netapp.com/advisory/ntap-20210716-0007/ Third Party Advisory
https://www.debian.org/security/2021/dsa-4924 Third Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-31808), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.