CVE-2021-31806

Name: CVE-2021-31806
Creator: NVD / NIST
Published: 2021-05-27T13:15:08.27+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 95.78%

Last modified Jun 17, 2026

CVE-2021-31806 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to a memory-management bug, it is vulnerable to a Denial of Service attack (against all clients using the proxy) via HTTP Range request processing.. EPSS estimates a 95.78% chance of exploitation in the next 30 days.

Description

An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to a memory-management bug, it is vulnerable to a Denial of Service attack (against all clients using the proxy) via HTTP Range request processing.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

95.78%

99.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-116

Affected Software

Vendor	Product	Versions
Squid-Cache	Squid	< 4.15
Squid-Cache	Squid	>= 5.0, < 5.0.6
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Fedoraproject	Fedora	33
Fedoraproject	Fedora	34
Netapp	Cloud Manager	All versions

References

http://seclists.org/fulldisclosure/2023/Oct/14Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/10/11/3Mailing List, Third Party Advisory
http://www.squid-cache.org/Versions/v4/changesets/squid-4-e7cf864f938f24eea8af0692c04d16790983c823.patchPatch, Vendor Advisory
https://github.com/squid-cache/squid/security/advisories/GHSA-pxwq-f3qr-w2xfPatch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00014.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2VCS6K3TKCF/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBTQHPBR6H66/
https://security.netapp.com/advisory/ntap-20210716-0007/Third Party Advisory
https://www.debian.org/security/2021/dsa-4924Third Party Advisory
http://seclists.org/fulldisclosure/2023/Oct/14Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/10/11/3Mailing List, Third Party Advisory
http://www.squid-cache.org/Versions/v4/changesets/squid-4-e7cf864f938f24eea8af0692c04d16790983c823.patchPatch, Vendor Advisory
https://github.com/squid-cache/squid/security/advisories/GHSA-pxwq-f3qr-w2xfPatch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00014.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2VCS6K3TKCF/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBTQHPBR6H66/
https://security.netapp.com/advisory/ntap-20210716-0007/Third Party Advisory
https://www.debian.org/security/2021/dsa-4924Third Party Advisory

Timeline

Published: May 27, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31806?

How severe is CVE-2021-31806?

CVE-2021-31806 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 95.78% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31806?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-31806?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST