CVE-2019-12526

An issue was discovered in Squid before 4.9. URN response handling in Squid suffers from a heap-based buffer overflow. When receiving data from a remote server in response to an URN request, Squid fails to ensure that the response can fit within the buffer. This leads to attacker controlled data overflowing in the heap.

Published: 2019-11-26 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2019-12526 is rated High Risk (72.5/100): CVSS Critical severity, with high exploitation likelihood (EPSS 38.43%, 97th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2019-12526

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-09 39.19% 38.43% -0.77%
2 2026-05-16 33.64% 39.19% +5.55%
3 2026-03-04 — 33.64% —

Full EPSS history (47 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-12526

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2019-12526

OS Trackers for CVE-2019-12526

vendor priority summary link
alpine critical CVE-2019-12526: 1 source package rows (squid); 10 state rows across 5 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 0, open 10. https://security.alpinelinux.org/vuln/CVE-2019-12526
debian not yet assigned CVE-2019-12526 not yet assigned priority: Debian including 1 source packages (squid), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2019-12526
gentoo normal CVE-2019-12526: 1 GLSA(s) (202003-34), 1 atom(s) (net-proxy/squid); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2019-12526
redhat medium — https://access.redhat.com/security/cve/CVE-2019-12526
suse high — https://www.suse.com/security/cve/CVE-2019-12526/
ubuntu medium CVE-2019-12526 medium priority: Ubuntu including 2 source packages (squid, squid3), 18 status rows across 9 suites (bionic, disco, eoan, focal, groovy, hirsute, trusty, upstream, xenial): DNE 9, released 8, needs-triage 1. https://ubuntu.com/security/CVE-2019-12526

Affected software / configurations for CVE-2019-12526

Vendor Product Version Raw CPE
squid-cache squid >= 3.0, <= 3.5.28 cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
squid-cache squid >= 4.0, <= 4.8 cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
canonical ubuntu_linux 16.04 cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 18.04 cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 19.04 cpe:2.3:o:canonical:ubuntu_linux:19.04:*:*:*:*:*:*:*
canonical ubuntu_linux 19.10 cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
fedoraproject fedora 30 cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
fedoraproject fedora 31 cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
opensuse leap 15.0 cpe:2.3:o:opensuse:leap:15.0:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2019-12526

URL Tags
http://www.squid-cache.org/Advisories/SQUID-2019_7.txt Third Party Advisory
https://bugzilla.suse.com/show_bug.cgi?id=1156326 Issue Tracking Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/12/msg00011.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html Mailing 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://security.gentoo.org/glsa/202003-34 Third Party Advisory
https://usn.ubuntu.com/4213-1/ Third Party Advisory
https://www.debian.org/security/2020/dsa-4682 Third Party Advisory
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