CVE-2019-18677

Name: CVE-2019-18677
Creator: NVD / NIST
Published: 2019-11-26T17:15:12.923+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 7.24%

Last modified Jun 17, 2026

CVE-2019-18677 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. An issue was discovered in Squid 3.x and 4.x through 4.8 when the append_domain setting is used (because the appended characters do not properly interact with hostname length restrictions). Due to incorrect message processing, it can inappropriately redirect traffic to origins it should not be delivered to.. EPSS estimates a 7.24% chance of exploitation in the next 30 days.

Description

An issue was discovered in Squid 3.x and 4.x through 4.8 when the append_domain setting is used (because the appended characters do not properly interact with hostname length restrictions). Due to incorrect message processing, it can inappropriately redirect traffic to origins it should not be delivered to.

Metrics

CVSS 3.1

6.1/10

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

EPSS Probability

7.24%

93.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-352

Affected Software

Vendor	Product	Versions	Update
Squid-Cache	Squid	>= 2.0, <= 2.7	—
Squid-Cache	Squid	>= 3.0, <= 3.5.28	—
Squid-Cache	Squid	>= 4.0, <= 4.8	—
Squid-Cache	Squid	2.7	Stable2
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	—

References

http://www.squid-cache.org/Advisories/SQUID-2019_9.txtThird Party Advisory
http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-e5f1813a674848dde570f7920873e1071f96e0b4.patchRelease Notes
http://www.squid-cache.org/Versions/v4/changesets/squid-4-36492033ea4097821a4f7ff3ddcb971fbd1e8ba0.patchRelease Notes
https://bugzilla.suse.com/show_bug.cgi?id=1156328Issue Tracking, Third Party Advisory
https://github.com/squid-cache/squid/pull/427Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/12/msg00011.htmlThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html
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://www.debian.org/security/2020/dsa-4682
http://www.squid-cache.org/Advisories/SQUID-2019_9.txtThird Party Advisory
http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-e5f1813a674848dde570f7920873e1071f96e0b4.patchRelease Notes
http://www.squid-cache.org/Versions/v4/changesets/squid-4-36492033ea4097821a4f7ff3ddcb971fbd1e8ba0.patchRelease Notes
https://bugzilla.suse.com/show_bug.cgi?id=1156328Issue Tracking, Third Party Advisory
https://github.com/squid-cache/squid/pull/427Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/12/msg00011.htmlThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html
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://www.debian.org/security/2020/dsa-4682

Timeline

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

Frequently Asked Questions

What is CVE-2019-18677?

How severe is CVE-2019-18677?

CVE-2019-18677 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 7.24% probability of exploitation in the next 30 days.

How do I fix CVE-2019-18677?

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-2019-18677?

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

Scan your code now

Source: NVD / NIST