Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured…
Priority MEDIUM 49CWE-264Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- — Not recorded in CVSS 2.0
- Attack complexity
- Medium
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- Partial · Partial · Partial
- Fix status
- Will not fix Red Hat: no fix planned
Attack profile from CVSS 2.0 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-264.
Summary
Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.
Why it matters now
EPSS 0.20844 97th percentileScored 2026-11-07
Public exploit Yes 4 exploit referencesTagged by NVD
Fix Will not fix Red Hat: no fix planned
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 · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:fedoraproject:fedora:22:*:*:*:*:*:*:* | 22 | Vulnerable | Fedoraproject |
| cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:* | 7.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:* | 8.0 | Vulnerable | Debian |
| cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:* | up to 3.5.2 | Vulnerable | squid-cache |
- cpe:2.3:o:fedoraproject:fedora:22:*:*:*:*:*:*:* Versions 22 Vulnerable ·Fedoraproject
- cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:* Versions 7.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Debian
- cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:* Versions up to 3.5.2 Vulnerable ·squid-cache
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 5 | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Will not fix |
Timeline
- 2026-10-02 Threatist record created from CVE-2015-5400
- 2026-10-03 Alias added: GHSA-9pj4-fqm8-w5x7
References
Exploit 4
Advisory 6
Sources
- CVE-2015-5400 · CVE Program
- CVE-2015-5400 · NVD
- FIRST EPSS
- GHSA-9pj4-fqm8-w5x7 · GitHub Advisory Database · CC BY 4.0
- CVE-2015-5400 · Red Hat security data · CC BY 4.0
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