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Fencer Vulns
medium 6.5

CVE-2024-23638 json

SQUID-2023:11 Denial of Service in Cache Manager

published 2024-01-23 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-21127

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
60.1%
EPSS 60.1% chance of exploitation in 30 days, percentile 99.1%
public exploits
0
none known

Summary

Squid is a caching proxy for the Web. Due to an expired pointer reference bug, Squid prior to version 6.6 is vulnerable to a Denial of Service attack against Cache Manager error responses. This problem allows a trusted client to perform Denial of Service when generating error pages for Client Manager reports. Squid older than 5.0.5 have not been tested and should be assumed to be vulnerable. All Squid-5.x up to and including 5.9 are vulnerable. All Squid-6.x up to and including 6.5 are vulnerable. This bug is fixed by Squid version 6.6. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. As a workaround, prevent access to Cache Manager using Squid's main access control: `http_access deny manager`.

Patch / fix

  • squid-cache squid 6.6
  • squid Debian 12 5.7-2+deb12u1
  • squid Debian 14, Debian 13 6.6-1

debian advisories DEBIAN-CVE-2024-23638

  • squid Ubuntu 20.04 LTS 4.10-1ubuntu1.10
  • squid Ubuntu 22.04 LTS 5.7-0ubuntu0.22.04.4

ubuntu advisories UBUNTU-CVE-2024-23638

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • squid RHEL 8 7:4.15-10.module+el8.10.0+22489+b920747d.3
  • libecap RHEL 8 1.0.1-2.module+el8.9.0+19703+a1da7223
  • squid RHEL 9 7:5.5-13.el9_4

red hat advisories RHSA-2024:9644RHSA-2024:4861

  • squid SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Module for Server Applications 15 SP5 +5 more 5.7-150400.3.23.1
  • squid SLES for SAP 15 SP3, SLES for SAP 15 SP2, SLES 15 SP3-LTSS +4 more 4.17-150000.5.49.1
  • squid SLES for SAP 12 SP5, SLES 12 SP5 4.17-4.41.1

suse advisories SUSE-SU-2024:0455-1SUSE-SU-2024:0298-1SUSE-SU-2024:0296-1

  • squid openSUSE Tumbleweed 6.6-2.1

opensuse advisories openSUSE-SU-2024:13631-1

  • squid AlmaLinux 8 7:4.15-10.module_el8.10.0+3916+ed00a4a0.3
  • libecap AlmaLinux 8 1.0.1-2.module_el8.6.0+2741+01592ae8
  • libecap AlmaLinux 8 1.0.1-2.module_el8.6.0+3048+383bc947
  • squid AlmaLinux 9 7:5.5-13.el9_4

almalinux advisories ALSA-2024:9644ALSA-2024:4861

  • squid Rocky Linux 8 7:4.15-10.module+el8.10.0+1758+80ba9f4b
  • libecap Rocky Linux 8 1.0.1-2.module+el8.9.0+1437+df5ea8f0
  • squid Rocky Linux 9 7:5.5-13.el9_4

rocky linux advisories RLSA-2024:9644RLSA-2024:4861

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-23638 updated cvss 6.5

squid: vulnerable to a Denial of Service attack against Cache Manager error responses

  • Red Hat Enterprise Linux 6 squid, squid34 Red Hat Enterprise Linux 7 squid, squid-sysvinit, squid-migration-script
    affected: workaround, no fix planned “Restrict entry to Cache Manager through Squid's primary access control: http_access deny manager”
  • Red Hat Enterprise Linux AppStream (v. 8) libecap 1.0.1-2.module+el8.9.0+19703+a1da7223, squid 4.15-10.module+el8.10.0+22489+b920747d.3
    fixed: vendor fix “Restrict entry to Cache Manager through Squid's primary access control: http_access deny manager” RHSA-2024:9644
  • Red Hat Enterprise Linux AppStream (v. 9) squid 5.5-13.el9_4
    fixed: vendor fix “Restrict entry to Cache Manager through Squid's primary access control: http_access deny manager” RHSA-2024:4861

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

60.05% chance of exploitation in the next 30 days, higher than 99.1% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • megamansec.github.io https://megamansec.github.io/Squid-Security-Audit/stream-assert.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • squid-cache squid

Classification

Weakness
  • CWE-825 Expired Pointer Dereference
  • CWE-672 Operation on a Resource after Expiration or Release

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.