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Fencer Vulns
high 8.6

CVE-2023-50269 in the critical feed json

SQUID-2023:10 Denial of Service in HTTP Request parsing

published 2023-12-14 2 y ago modified 2026-06-17 4 mo ago also EUVD-2023-55081

cvss
8.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
57.6%
EPSS 57.6% chance of exploitation in 30 days, percentile 99%
public exploits
0
none known

Summary

Squid is a caching proxy for the Web. Due to an Uncontrolled Recursion bug in versions 2.6 through 2.7.STABLE9, versions 3.1 through 5.9, and versions 6.0.1 through 6.5, Squid may be vulnerable to a Denial of Service attack against HTTP Request parsing. This problem allows a remote client to perform Denial of Service attack by sending a large X-Forwarded-For header when the follow_x_forwarded_for feature is configured. 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.

Patch / fix

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

debian advisories DEBIAN-CVE-2023-50269

  • squid Ubuntu 20.04 LTS 4.10-1ubuntu1.9
  • squid Ubuntu 22.04 LTS 5.7-0ubuntu0.22.04.3
  • squid Ubuntu 24.04 LTS 6.5-1ubuntu3
  • squid3 Ubuntu Pro 16.04 LTS 3.5.12-1ubuntu7.16+esm3
  • squid3 Ubuntu Pro 18.04 LTS 3.5.27-1ubuntu1.14+esm2

ubuntu advisories UBUNTU-CVE-2023-50269

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 7 7:3.5.20-17.el7_9.10
  • squid-sysvinit RHEL 7 7:3.5.20-17.el7_9.10
  • squid-migration-script RHEL 7 7:3.5.20-17.el7_9.10
  • squid RHEL 9 7:5.5-6.el9_3.8
  • squid RHEL 8 7:4.15-7.module+el8.9.0+21530+59b09a5b.10
  • libecap RHEL 8 1.0.1-2.module+el8.9.0+19703+a1da7223
  • squid RHEL 9.0 EUS 7:5.2-1.el9_0.4
  • squid RHEL 9.2 EUS 7:5.5-5.el9_2.4

red hat advisories RHSA-2024:1787RHSA-2024:1376RHSA-2024:1375RHSA-2024:1153RHSA-2024:1085RHSA-2024:0771

  • 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 7:4.15-7.module_el8.9.0+3749+dbf371ed.10
  • 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 7:5.5-6.el9_3.8

almalinux advisories ALSA-2024:1375ALSA-2024:1376

  • libecap Rocky Linux 8 1.0.1-2.module+el8.9.0+1437+df5ea8f0

rocky linux advisories RLSA-2024:1375

  • squid Alpine 3.24, Alpine 3.23, Alpine 3.22 +3 more 6.6-r0

alpine advisories ALPINE-CVE-2023-50269

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2023-50269 updated cvss 7.5

squid: denial of service in HTTP request parsing

  • Red Hat Enterprise Linux 6 squid, squid34
    affected: workaround, no fix planned “Remove all "follow_x_forwarded_for" lines from squid.conf.”
  • Red Hat Enterprise Linux AppStream (v. 8) libecap 1.0.1-2.module+el8.9.0+19703+a1da7223, squid 4.15-7.module+el8.9.0+21530+59b09a5b.10
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:1375
  • Red Hat Enterprise Linux AppStream (v. 9) squid 5.5-6.el9_3.8
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:1376
  • Red Hat Enterprise Linux AppStream AUS (v. 8.2) squid 4.4-8.module+el8.2.0+21173+22259b09.7, libecap 1.0.1-2.module+el8.1.0+4044+36416a77
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:0772
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) libecap 1.0.1-2.module+el8.1.0+4044+36416a77, squid 4.11-4.module+el8.4.0+21174+3894a031.6
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:0773
  • Red Hat Enterprise Linux AppStream E4S (v. 8.2) squid 4.4-8.module+el8.2.0+21173+22259b09.7, libecap 1.0.1-2.module+el8.1.0+4044+36416a77
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:0772
  • Red Hat Enterprise Linux AppStream E4S (v.8.4) libecap 1.0.1-2.module+el8.1.0+4044+36416a77, squid 4.11-4.module+el8.4.0+21174+3894a031.6
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:0773
  • Red Hat Enterprise Linux AppStream EUS (v.8.6) libecap 1.0.1-2.module+el8.1.0+4044+36416a77, squid 4.15-3.module+el8.6.0+21069+a1561e3d.4
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:0771
show 6 more
  • Red Hat Enterprise Linux AppStream EUS (v.8.8) libecap 1.0.1-2.module+el8.1.0+4044+36416a77, squid 4.15-6.module+el8.8.0+21068+0ecbc070.3
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:0397
  • Red Hat Enterprise Linux AppStream EUS (v.9.0) squid 5.2-1.el9_0.4
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:1153
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) squid 5.5-5.el9_2.4
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:1085
  • Red Hat Enterprise Linux AppStream TUS (v. 8.2) squid 4.4-8.module+el8.2.0+21173+22259b09.7, libecap 1.0.1-2.module+el8.1.0+4044+36416a77
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:0772
  • Red Hat Enterprise Linux AppStream TUS (v.8.4) libecap 1.0.1-2.module+el8.1.0+4044+36416a77, squid 4.11-4.module+el8.4.0+21174+3894a031.6
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:0773
  • Red Hat Enterprise Linux Server (v. 7) squid 3.5.20-17.el7_9.10, squid-sysvinit 3.5.20-17.el7_9.10, squid-migration-script 3.5.20-17.el7_9.10 Red Hat Enterprise Linux Server Optional (v. 7) squid 3.5.20-17.el7_9.10, squid-sysvinit 3.5.20-17.el7_9.10, squid-migration-script 3.5.20-17.el7_9.10 Red Hat Enterprise Linux Workstation (v. 7) squid 3.5.20-17.el7_9.10, squid-sysvinit 3.5.20-17.el7_9.10, squid-migration-script 3.5.20-17.el7_9.10 Red Hat Enterprise Linux Workstation Optional (v. 7) squid 3.5.20-17.el7_9.10, squid-sysvinit 3.5.20-17.el7_9.10, squid-migration-script 3.5.20-17.el7_9.10
    fixed: vendor fix “Remove all "follow_x_forwarded_for" lines from squid.conf.” RHSA-2024:1787

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
none
Automatable
yes
Technical impact
partial
Assessed
2 y ago

Exploit prediction

57.63% chance of exploitation in the next 30 days, higher than 99% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • squid-cache squid

Classification

Weakness

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.