CVE-2019-18676

Name: CVE-2019-18676
Creator: NVD / NIST
Published: 2019-11-26T17:15:12.843+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 9.18%

Last modified Jun 17, 2026

CVE-2019-18676 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. EPSS estimates a 9.18% chance of exploitation in the next 30 days.

Description

An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity is high due to this vulnerability occurring before normal security checks; any remote client that can reach the proxy port can trivially perform the attack via a crafted URI scheme.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

9.18%

94.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-787

Affected Software

Vendor	Product	Versions
Squid-Cache	Squid	>= 3.0, <= 3.5.28
Squid-Cache	Squid	>= 4.0, <= 4.8
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	19.04
Canonical	Ubuntu Linux	19.10
Fedoraproject	Fedora	30
Fedoraproject	Fedora	31
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0

References

http://www.squid-cache.org/Advisories/SQUID-2019_8.txtThird Party Advisory
http://www.squid-cache.org/Versions/v4/changesets/squid-4-fbbdf75efd7a5cc244b4886a9d42ea458c5a3a73.patchPatch
https://bugzilla.suse.com/show_bug.cgi?id=1156329Issue Tracking, Third Party Advisory
https://github.com/squid-cache/squid/pull/275Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MTM74TU2BSLT5B3H4F3UDW53672NVLMC/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UEMOYTMCCFWK5NOXSXEIH5D2VGWVXR67/
https://usn.ubuntu.com/4213-1/Third Party Advisory
https://usn.ubuntu.com/4446-1/Third Party Advisory
https://www.debian.org/security/2020/dsa-4682Third Party Advisory
http://www.squid-cache.org/Advisories/SQUID-2019_8.txtThird Party Advisory
http://www.squid-cache.org/Versions/v4/changesets/squid-4-fbbdf75efd7a5cc244b4886a9d42ea458c5a3a73.patchPatch
https://bugzilla.suse.com/show_bug.cgi?id=1156329Issue Tracking, Third Party Advisory
https://github.com/squid-cache/squid/pull/275Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MTM74TU2BSLT5B3H4F3UDW53672NVLMC/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UEMOYTMCCFWK5NOXSXEIH5D2VGWVXR67/
https://usn.ubuntu.com/4213-1/Third Party Advisory
https://usn.ubuntu.com/4446-1/Third Party Advisory
https://www.debian.org/security/2020/dsa-4682Third Party Advisory

Timeline

Published: Nov 26, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-18676?

How severe is CVE-2019-18676?

CVE-2019-18676 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 9.18% probability of exploitation in the next 30 days.

How do I fix CVE-2019-18676?

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-2019-18676?

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

Scan your code now

Source: NVD / NIST