Public Date:
1536942: CVE-2018-1000027 squid: Incorrect pointer handling in HTTP processing and certificate download can lead to denial of service

The MITRE CVE dictionary describes this issue as:

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.

Find out more about CVE-2018-1000027 from the MITRE CVE dictionary dictionary and NIST NVD.

CVSS v3 metrics

NOTE: The following CVSS v3 metrics and score provided are preliminary and subject to review.

CVSS3 Base Score 6.8
CVSS3 Base Metrics CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction None
Scope Changed
Confidentiality None
Integrity Impact None
Availability Impact High

Affected Packages State

Platform Package State
Red Hat Enterprise Linux 8 squid Not affected
Red Hat Enterprise Linux 7 squid Will not fix
Red Hat Enterprise Linux 6 squid34 Will not fix
Red Hat Enterprise Linux 6 squid Will not fix
Red Hat Enterprise Linux 5 squid Not affected
Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.


A workaround for this issue is to set the "log_uses_indirect_client off" configuration directive in the squid configuration file (for example /etc/squid/squid.conf).

Last Modified

CVE description copyright © 2017, The MITRE Corporation