CVE-2018-1000024
squid: Incorrect pointer handling when processing ESI Responses can lead to denial of service
Severity
ModerateRed Hat Product Security
CVSS 3.0
Review impact separately from score.
Published · January 19, 2018
Updated · January 14, 2026
Description
The Squid Software Foundation Squid HTTP Caching Proxy version 3.0 to 3.5.27, 4.0 to 4.0.22 contains a Incorrect Pointer Handling vulnerability in ESI Response Processing that can result in Denial of Service for all clients using the proxy.. This attack appear to be exploitable via Remote server delivers an HTTP response payload containing valid but unusual ESI syntax.. This vulnerability appears to have been fixed in 4.0.23 and later.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
A workaround for this issue is to not use the internal ESI parser, which can be achieved by adding either the "esi_parser expat" or "esi_parser libxml2" configuration directive to the squid configuration file (for example /etc/squid/squid.conf).
CVSS / CWE
CVSS 3.0 · 7.4CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:N/A:H
CWE-20 · Improper Input Validation