No exploitation reported

CVE-2019-12523

No exploitation reported by the sources we read.

Published2019-11-26

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2019-11-2617:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2019-12523?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2019-12523?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Canonical ubuntu linux

Branch	Affected	Fixed in	Source
16.4	= 16.04	no fix published	NVD
18.4	= 18.04	no fix published	NVD
19.4	= 19.04	no fix published	NVD
19.10	= 19.10	no fix published	NVD

Debian debian linux

Branch	Affected	Fixed in	Source
9.0	= 9.0	no fix published	NVD
10.0	= 10.0	no fix published	NVD

Fedoraproject fedora

Branch	Affected	Fixed in	Source
30.x	= 30	no fix published	NVD
31.x	= 31	no fix published	NVD

2 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

libecapAlmaLinux:8all versions · fixed in 1.0.1-2.module_el8.6.0+2741+01592ae8and 1 other package

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.19.1read 2026-10-23
NVDCVSS 2.06.4read 2026-10-23
FIRST EPSSEPSS score4.3 %2026-10-22
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Published: 2019-11-26
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2019-12523?

Is CVE-2019-12523 actively exploited?

Active exploitation of CVE-2019-12523 has not been confirmed. Its EPSS score was 4.3% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2019-12523?

CVE-2019-12523 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

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