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Fencer Vulns
high 8.6

CVE-2023-46724 json

SQUID-2023:4 Denial of Service in SSL Certificate validation

published 2023-11-01 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-50907

cvss
8.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.8%
EPSS 2.8% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

Squid is a caching proxy for the Web. Due to an Improper Validation of Specified Index bug, Squid versions 3.3.0.1 through 5.9 and 6.0 prior to 6.4 compiled using `--with-openssl` are vulnerable to a Denial of Service attack against SSL Certificate validation. This problem allows a remote server to perform Denial of Service against Squid Proxy by initiating a TLS Handshake with a specially crafted SSL Certificate in a server certificate chain. This attack is limited to HTTPS and SSL-Bump. This bug is fixed in Squid version 6.4. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. Those who you use a prepackaged version of Squid should refer to the package vendor for availability information on updated packages.

Patch / fix

  • squid-cache squid 6.4
  • squid Debian 12 5.7-2+deb12u1
  • squid Debian 14, Debian 13 6.5-1

debian advisories DEBIAN-CVE-2023-46724

  • squid Ubuntu 22.04 LTS 5.7-0ubuntu0.22.04.2
  • squid Ubuntu 24.04 LTS 6.1-2ubuntu2

ubuntu advisories UBUNTU-CVE-2023-46724

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_3.5
  • squid RHEL 8 7:4.15-7.module+el8.9.0+20975+25f17541.5
  • 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 8.6 EUS 7:4.15-3.module+el8.6.0+21069+a1561e3d.4

red hat advisories RHSA-2024:1787RHSA-2024:1153RHSA-2024:0771RHSA-2024:0772RHSA-2024:0773RHSA-2024:0397

  • squid SLES for SAP 15 SP3, SLES for SAP 15 SP2, SLES for SAP 15 SP1 +8 more 4.17-150000.5.38.1
  • squid SLES for SAP 12 SP5, SLES 12 SP5 4.17-4.30.1
  • squid SLE Module for Server Applications 15 SP5, SLE Module for Server Applications 15 SP4, openSUSE Leap 15.5 +1 more 5.7-150400.3.12.1

suse advisories SUSE-SU-2023:4384-1SUSE-SU-2023:4381-1SUSE-SU-2023:4380-1

  • squid openSUSE Tumbleweed 6.4-1.1

opensuse advisories openSUSE-SU-2024:13398-1

  • squid AlmaLinux 9 7:5.5-6.el9_3.5
  • squid AlmaLinux 8 7:4.15-7.module_el8.9.0+3708+6acaac63.5
  • 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

almalinux advisories ALSA-2024:0071ALSA-2024:0046

  • squid Rocky Linux 8 7:4.15-7.module+el8.9.0+1568+6d4fd5d4.1
  • libecap Rocky Linux 8 1.0.1-2.module+el8.9.0+1437+df5ea8f0

rocky linux advisories RLSA-2024:0046

  • squid Alpine 3.24, Alpine 3.23, Alpine 3.22 +3 more 6.4-r0

alpine advisories ALPINE-CVE-2023-46724

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-2023-46724 updated cvss 7.5

squid: Denial of Service in SSL Certificate validation

  • Red Hat Enterprise Linux 6 squid, squid34
    affected: workaround, no fix planned “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives from squid.conf”
  • Red Hat Enterprise Linux AppStream (v. 8) squid 4.15-7.module+el8.9.0+20975+25f17541.5, libecap 1.0.1-2.module+el8.9.0+19703+a1da7223
    fixed: vendor fix “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives from squid.conf” RHSA-2024:0046
  • Red Hat Enterprise Linux AppStream (v. 9) squid 5.5-6.el9_3.5
    fixed: vendor fix “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives from squid.conf” RHSA-2024:0071
  • 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 “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives 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 “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives 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 “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives 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 “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives 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 “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives 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 “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives 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 “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives from squid.conf” RHSA-2024:1153
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) squid 5.5-5.el9_2.3
    fixed: vendor fix “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives from squid.conf” RHSA-2024:0072
  • 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 “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives 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 “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives from squid.conf” RHSA-2024:0773
  • Red Hat Enterprise Linux Server (v. 7) squid 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-sysvinit 3.5.20-17.el7_9.10 Red Hat Enterprise Linux Workstation (v. 7) squid 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-sysvinit 3.5.20-17.el7_9.10
    fixed: vendor fix “Disable the use of SSL-Bump features: - Remove all ssl-bump options from http_port and https_port - Remove all ssl_bump directives 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

2.81% chance of exploitation in the next 30 days, higher than 86% 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
  • CWE-125 Out-of-bounds Read
  • CWE-129 Improper Validation of Array Index
  • CWE-786 Access of Memory Location Before Start of Buffer
  • CWE-823 Use of Out-of-range Pointer Offset
  • CWE-1285 Improper Validation of Specified Index, Position, or Offset in Input
  • CWE-295 Improper Certificate Validation

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.