Detections
Analytics

CentOS Linux 6 [TuxCare] Security Update: squid Multiple Vulnerabilities (CENTOS6:CLSA-2026:1777446517)

critical Nessus Plugin ID 362335

Language:

Synopsis

The CentOS Linux host is missing one or more security updates.

Description

The CentOS Linux 6 host has a package installed that is affected by multiple vulnerabilities as referenced in the TuxCare CENTOS6:CLSA-2026:1777446517 advisory.

 - An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.
 (CVE-2019-12521)

 - An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to see if the request should be denied. Squid by default comes with rules to block access to the Cache Manager, which serves detailed server information meant for the maintainer. This rule is implemented via url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to encode their URL to bypass the url_regex check, and gain access to the blocked resource. (CVE-2019-12524)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Update the affected squid package based on the guidance in TuxCare advisory CENTOS6:CLSA-2026:1777446517.

See Also

https://cve.tuxcare.com/els/releases/CLSA-2026:1777446517

http://www.nessus.org/u?bba3b7d4

Plugin Details

Severity: Critical

ID: 362335

File Name: tuxcare_centos_6_CLSA-2026-1777446517.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 10/1/2026

Updated: 10/1/2026

Supported Sensors: Continuous Assessment, Nessus Agent, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 57.12

Vendor

Vendor Severity: Critical

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 5.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2019-12524

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Required KB Items: Host/OS/extended-third-party, Host/local_checks_enabled, Host/CentOS/release, Host/CentOS/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 4/29/2026

Vulnerability Publication Date: 4/15/2020

Reference Information

CVE: CVE-2019-12521, CVE-2019-12524

CLSA: 2026:1777446517