CVE-2019-12523

Name: CVE-2019-12523
Creator: NVD / NIST
Published: 2019-11-26T17:15:10.767+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.1/10EPSS 4.30%

Last modified Jun 17, 2026

CVE-2019-12523 is a critical-severity vulnerability rated 9.1/10 on the CVSS scale. An issue was discovered in Squid before 4.9. When handling a URN request, a corresponding HTTP request is made. EPSS estimates a 4.30% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

9.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS Probability

4.30%

89.9th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Squid-Cache	Squid	>= 3.0, <= 3.5.28
Squid-Cache	Squid	>= 4.0, <= 4.8
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	19.04
Canonical	Ubuntu Linux	19.10
Fedoraproject	Fedora	30
Fedoraproject	Fedora	31
Opensuse	Leap	15.0
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0

References

http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00056.htmlBroken Link
http://www.squid-cache.org/Advisories/SQUID-2019_8.txtThird Party Advisory
https://bugzilla.suse.com/show_bug.cgi?id=1156329Issue Tracking, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MTM74TU2BSLT5B3H4F3UDW53672NVLMC/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UEMOYTMCCFWK5NOXSXEIH5D2VGWVXR67/
https://usn.ubuntu.com/4213-1/Third Party Advisory
https://usn.ubuntu.com/4446-1/Third Party Advisory
https://www.debian.org/security/2020/dsa-4682Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00056.htmlBroken Link
http://www.squid-cache.org/Advisories/SQUID-2019_8.txtThird Party Advisory
https://bugzilla.suse.com/show_bug.cgi?id=1156329Issue Tracking, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MTM74TU2BSLT5B3H4F3UDW53672NVLMC/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UEMOYTMCCFWK5NOXSXEIH5D2VGWVXR67/
https://usn.ubuntu.com/4213-1/Third Party Advisory
https://usn.ubuntu.com/4446-1/Third Party Advisory
https://www.debian.org/security/2020/dsa-4682Third Party Advisory

Timeline

Published: Nov 26, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-12523?

How severe is CVE-2019-12523?

CVE-2019-12523 has a CVSS score of 9.1/10 (CRITICAL severity). The EPSS model estimates a 4.30% probability of exploitation in the next 30 days.

How do I fix CVE-2019-12523?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-12523?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST