An issue was discovered in Squid before 4.9.
Priority MEDIUM 46Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Partial Red Hat: 1 fixed, 2 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
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.
Why it matters now
EPSS 0.04302 91st percentileScored 2026-11-07
Fix Partial Red Hat: 1 advisoryRed Hat: 1 fixed, 2 without a fix
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 11
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:* | 3.0 – 3.5.28; 4.0 – 4.8 | Vulnerable | squid-cache |
| cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:* | 16.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:* | 18.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:19.04:*:*:*:*:*:*:* | 19.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:* | 19.10 | Vulnerable | Canonical |
| cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:* | 30 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:* | 31 | Vulnerable | Fedoraproject |
| cpe:2.3:o:opensuse:leap:15.0:*:*:*:*:*:*:* | 15.0 | Vulnerable | openSUSE |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
- cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:* Versions 3.0 – 3.5.28; 4.0 – 4.8 Vulnerable ·squid-cache
- cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:* Versions 16.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:* Versions 18.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:19.04:*:*:*:*:*:*:* Versions 19.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:* Versions 19.10 Vulnerable ·Canonical
- cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:* Versions 30 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:* Versions 31 Vulnerable ·Fedoraproject
- cpe:2.3:o:opensuse:leap:15.0:*:*:*:*:*:*:* Versions 15.0 Vulnerable ·openSUSE
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
Remediation
Red Hat 1 advisory
- RHSA-2020:4743 Released 2020-11-04 · Red Hat rating Moderatesquid:4 security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 8) libecap-1.0.1-2.module+el8.1.0+4044+36416a77.aarch64::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.ppc64le::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.s390x::squid:4 +11
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2020:4743 |
Not affected: 1 product
- Red Hat Enterprise Linux 5
Timeline
- 2026-10-02 Threatist record created from CVE-2019-12523
- 2026-10-03 Alias added: GHSA-99vq-f459-jqrg
References
Advisory 8
Sources
- CVE-2019-12523 · CVE Program
- CVE-2019-12523 · NVD
- FIRST EPSS
- GHSA-99vq-f459-jqrg · GitHub Advisory Database · CC BY 4.0
- CVE-2019-12523 · Red Hat security data · CC BY 4.0
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