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Vulnerability record · CVE-2019-12523 · published 26 November 2019

CVE-2019-12523: Squid-cache squid vulnerability

Squid Cache · Squid

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.

9.1 CVSS 3.1 Critical EPSS 4.3% · top 9.2%
9.1CVSS 3.1 base score, v2 6.4
4.3%EPSS exploitation probability, 30 days
NoNot in CISA KEV
5Affected product versions listed by NVD
18References
17 Jun 2026Last modified by NVD

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.

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

Affected products

5 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00056.html Broken Link
http://www.squid-cache.org/Advisories/SQUID-2019_8.txt Third Party Advisory
https://bugzilla.suse.com/show_bug.cgi?id=1156329 Issue TrackingThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MTM74TU2BSLT5B3H4F3UDW5
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UEMOYTMCCFWK5NOXSXEIH5D
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-4682 Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00056.html Broken Link
http://www.squid-cache.org/Advisories/SQUID-2019_8.txt Third Party Advisory
https://bugzilla.suse.com/show_bug.cgi?id=1156329 Issue TrackingThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MTM74TU2BSLT5B3H4F3UDW5
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UEMOYTMCCFWK5NOXSXEIH5D
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-4682 Third Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2019-12523), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.