CVE-2019-18678

Name: CVE-2019-18678
Creator: NVD / NIST
Published: 2019-11-26T17:15:12.983+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 10.93%

Last modified Jun 17, 2026

CVE-2019-18678 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. An issue was discovered in Squid 3.x and 4.x through 4.8. It allows attackers to smuggle HTTP requests through frontend software to a Squid instance that splits the HTTP Request pipeline differently. EPSS estimates a 10.93% chance of exploitation in the next 30 days.

Description

An issue was discovered in Squid 3.x and 4.x through 4.8. It allows attackers to smuggle HTTP requests through frontend software to a Squid instance that splits the HTTP Request pipeline differently. The resulting Response messages corrupt caches (between a client and Squid) with attacker-controlled content at arbitrary URLs. Effects are isolated to software between the attacker client and Squid. There are no effects on Squid itself, nor on any upstream servers. The issue is related to a request header containing whitespace between a header name and a colon.

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

10.93%

95.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-444

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
Debian	Debian Linux	8.0
Fedoraproject	Fedora	30
Fedoraproject	Fedora	31

References

http://www.squid-cache.org/Advisories/SQUID-2019_10.txtThird Party Advisory
http://www.squid-cache.org/Versions/v4/changesets/squid-4-671ba97abe929156dc4c717ee52ad22fba0f7443.patchRelease Notes
https://bugzilla.suse.com/show_bug.cgi?id=1156323Issue Tracking, Third Party Advisory
https://github.com/squid-cache/squid/pull/445Patch, 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://security.gentoo.org/glsa/202003-34
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_10.txtThird Party Advisory
http://www.squid-cache.org/Versions/v4/changesets/squid-4-671ba97abe929156dc4c717ee52ad22fba0f7443.patchRelease Notes
https://bugzilla.suse.com/show_bug.cgi?id=1156323Issue Tracking, Third Party Advisory
https://github.com/squid-cache/squid/pull/445Patch, 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://security.gentoo.org/glsa/202003-34
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-2019-18678?

How severe is CVE-2019-18678?

CVE-2019-18678 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 10.93% probability of exploitation in the next 30 days.

How do I fix CVE-2019-18678?

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-2019-18678?

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

Scan your code now

Source: NVD / NIST