CVE-2021-31807

Name: CVE-2021-31807
Creator: NVD / NIST
Published: 2021-06-08T20:15:09.057+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 15.97%

Last modified Jun 17, 2026

CVE-2021-31807 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. An integer overflow problem allows a remote server to achieve Denial of Service when delivering responses to HTTP Range requests. EPSS estimates a 15.97% 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. An integer overflow problem allows a remote server to achieve Denial of Service when delivering responses to HTTP Range requests. The issue trigger is a header that can be expected to exist in HTTP traffic without any malicious intent.

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

15.97%

96.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-190

Affected Software

Vendor	Product	Versions
Squid-Cache	Squid	>= 3.0, < 4.15
Squid-Cache	Squid	>= 5.0, < 5.0.6
Squid-Cache	Squid	2.5.stable2
Squid-Cache	Squid	2.5.stable3
Squid-Cache	Squid	2.5.stable4
Squid-Cache	Squid	2.5.stable5
Squid-Cache	Squid	2.5.stable6
Squid-Cache	Squid	2.5.stable7
Squid-Cache	Squid	2.5.stable8
Squid-Cache	Squid	2.5.stable9
Squid-Cache	Squid	2.5.stable10
Squid-Cache	Squid	2.5.stable11
Squid-Cache	Squid	2.5.stable12
Squid-Cache	Squid	2.5.stable13
Squid-Cache	Squid	2.5.stable14
Squid-Cache	Squid	2.6
Squid-Cache	Squid	2.7
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-w2xfThird 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
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-w2xfThird 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

Timeline

Published: Jun 8, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31807?

How severe is CVE-2021-31807?

CVE-2021-31807 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 15.97% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31807?

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-2021-31807?

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

Scan your code now

Source: NVD / NIST