CVE-2019-12523

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 4.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2019-11-26 · updated 2026-06-17

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.

Affected products

Canonical Ubuntu Linux: 16.04, 18.04, 19.04, 19.10
Debian Linux: 9.0, 10.0
Fedoraproject Fedora: 30, 31
openSUSE Leap: 15.0
Squid: from 3.0 through 3.5.28; from 4.0 through 4.8

References

http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00056.html
http://www.squid-cache.org/Advisories/SQUID-2019_8.txt
https://bugzilla.suse.com/show_bug.cgi?id=1156329
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html
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/
https://usn.ubuntu.com/4446-1/
https://www.debian.org/security/2020/dsa-4682
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00056.html
http://www.squid-cache.org/Advisories/SQUID-2019_8.txt
https://bugzilla.suse.com/show_bug.cgi?id=1156329

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