CVE-2018-1000027

Name: CVE-2018-1000027
Creator: NVD / NIST
Published: 2018-02-09T23:29:00.87+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 13.15%

Last modified Jun 17, 2026

CVE-2018-1000027 is a vulnerability of currently unknown severity. The Squid Software Foundation Squid HTTP Caching Proxy version prior to version 4.0.23 contains a NULL Pointer Dereference vulnerability in HTTP Response X-Forwarded-For header processing that can result in Denial of Service to all clients of the proxy. This attack appear to be exploitable via Remote HTTP server responding with an X-Forwarded-For header to certain types of HTTP request. EPSS estimates a 13.15% chance of exploitation in the next 30 days.

Description

The Squid Software Foundation Squid HTTP Caching Proxy version prior to version 4.0.23 contains a NULL Pointer Dereference vulnerability in HTTP Response X-Forwarded-For header processing that can result in Denial of Service to all clients of the proxy. This attack appear to be exploitable via Remote HTTP server responding with an X-Forwarded-For header to certain types of HTTP request. This vulnerability appears to have been fixed in 4.0.23 and later.

Metrics

EPSS Probability

13.15%

95.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-476

Affected Software

Vendor	Product	Versions
Squid-Cache	Squid	< 4.0.23
Debian	Debian Linux	7.0
Debian	Debian Linux	8.0
Debian	Debian Linux	9.0
Canonical	Ubuntu Linux	14.04
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	17.10

References

http://www.squid-cache.org/Advisories/SQUID-2018_2.txtPatch, Vendor Advisory
http://www.squid-cache.org/Versions/v3/3.5/changesets/SQUID-2018_2.patchPatch, Vendor Advisory
http://www.squid-cache.org/Versions/v4/changesets/SQUID-2018_2.patchPatch, Vendor Advisory
https://github.com/squid-cache/squid/pull/129/filesThird Party Advisory
https://lists.debian.org/debian-lts-announce/2018/02/msg00001.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2018/02/msg00002.htmlMailing List, Third Party Advisory
https://usn.ubuntu.com/3557-1/Third Party Advisory
https://usn.ubuntu.com/4059-2/
https://www.debian.org/security/2018/dsa-4122Third Party Advisory
http://www.squid-cache.org/Advisories/SQUID-2018_2.txtPatch, Vendor Advisory
http://www.squid-cache.org/Versions/v3/3.5/changesets/SQUID-2018_2.patchPatch, Vendor Advisory
http://www.squid-cache.org/Versions/v4/changesets/SQUID-2018_2.patchPatch, Vendor Advisory
https://github.com/squid-cache/squid/pull/129/filesThird Party Advisory
https://lists.debian.org/debian-lts-announce/2018/02/msg00001.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2018/02/msg00002.htmlMailing List, Third Party Advisory
https://usn.ubuntu.com/3557-1/Third Party Advisory
https://usn.ubuntu.com/4059-2/
https://www.debian.org/security/2018/dsa-4122Third Party Advisory

Timeline

Published: Feb 9, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-1000027?

How severe is CVE-2018-1000027?

Severity scoring for CVE-2018-1000027 is pending analysis. The EPSS model estimates a 13.15% probability of exploitation in the next 30 days.

How do I fix CVE-2018-1000027?

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-2018-1000027?

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

Scan your code now

Source: NVD / NIST