Skip to content
Fencer Vulns
critical 9.1

CVE-2019-12523 json

An issue was discovered in Squid before 4.9.

published 2019-11-26 6 y ago modified 2026-06-17 4 mo ago also EUVD-2019-4118

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.3%
EPSS 4.3% chance of exploitation in 30 days, percentile 91%
public exploits
0
none known

Summary

An issue was discovered in Squid before 4.9. When handling a URN request, a corresponding HTTP request is made. This HTTP request doesn't go through the access checks that incoming HTTP requests go through. This causes all access checks to be bypassed and allows access to restricted HTTP servers, e.g., an attacker can connect to HTTP servers that only listen on localhost.

Patch / fix

  • squid Debian 14, Debian 13, Debian 12 4.9-1

debian advisories DEBIAN-CVE-2019-12523

  • squid Ubuntu 20.04 LTS 4.9-2ubuntu1
  • squid3 Ubuntu 16.04 LTS 3.5.12-1ubuntu7.12
  • squid3 Ubuntu 18.04 LTS 3.5.27-1ubuntu1.7

ubuntu advisories UBUNTU-CVE-2019-12523

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 7:4.11-3.module+el8.3.0+7851+7808b5f9
  • libecap RHEL 8 1.0.1-2.module+el8.1.0+4044+36416a77

red hat advisories RHSA-2020:4743

  • squid SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 2.7.STABLE5-2.12.30.6.1
  • squid3 SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 3.1.23-8.16.37.12.1
  • squid SLES for SAP 12 SP4, SLES for SAP 12 SP3, SLES for SAP 12 SP2 +10 more 3.5.21-26.20.1
  • squid SLES for SAP 12 SP5, SLES 12 SP5 4.9-4.3.2
  • squid SLE Module for Server Applications 15 SP1, SLE Module for Server Applications 15 4.9-5.11.1

suse advisories SUSE-SU-2022:14908-1SUSE-SU-2020:14460-1SUSE-SU-2020:0661-1SUSE-SU-2019:3067-1SUSE-SU-2019:2975-1

  • squid openSUSE Tumbleweed 4.16-1.5
  • squid openSUSE Leap 15.1 4.9-lp151.2.7.1
  • squid openSUSE Leap 15.0 4.9-lp150.13.1

opensuse advisories openSUSE-SU-2024:11403-1openSUSE-SU-2019:2541-1openSUSE-SU-2019:2540-1

  • libecap AlmaLinux 8 1.0.1-2.module_el8.6.0+2741+01592ae8

almalinux advisories ALSA-2020:4743

  • libecap Rocky Linux 8 1.0.1-2.module+el8.4.0+404+316a0dc5

rocky linux advisories RLSA-2020:4743

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-2019-12523 updated cvss 7.4

squid: Improper input validation in URI processor

  • Red Hat Enterprise Linux 6 squid, squid34 Red Hat Enterprise Linux 7 squid, squid-sysvinit, squid-migration-script
    affected: workaround, no fix planned “Access to manager services can be prevented by enabling the Via header: (in /etc/squid/squid.conf) ~~~ via on ~~~ There are no reliable workarounds to prevent access to restricted upstream servers.”
  • Red Hat Enterprise Linux AppStream (v. 8) squid 4.11-3.module+el8.3.0+7851+7808b5f9, libecap 1.0.1-2.module+el8.1.0+4044+36416a77
    fixed: vendor fix “Access to manager services can be prevented by enabling the Via header: (in /etc/squid/squid.conf) ~~~ via on ~~~ There are no reliable workarounds to prevent access to restricted upstream servers.” RHSA-2020:4743
  • Red Hat Enterprise Linux 5 squid
    not affected: vulnerable code not present

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

Exploit prediction

4.30% chance of exploitation in the next 30 days, higher than 91% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:P/A:N

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.