Squid Request Smuggling in HTTP Transfer-Encoding (squid-cache squid)
At a glance
- Source
- NVD
- EPSS
- EPSS 2.04 % · percentile 81 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Awaiting Analysis
Description
Squid is a caching proxy for the Web. From 3.3.0.1 to before 7.6, due to an improper enforcement of behavioral workflow bug, Squid is vulnerable to a Request Smuggling attack against HTTP/1.1 Transfer-Encoding. HTTP header parsing (`src/HttpHeader.cc`) accepted the bare` Transfer-Encoding:` identity form, which the HTTP specification prohibits because any transfer coding must be wrapped within chunked encoding. This problem allows a trusted client to perform an HTTP Request Smuggling attack when HTTP/1.1 is used, bypassing security mechanisms that may be in place between attacker and Squid. When there is an HTTP cache operating prior to the affected Squid, this Request Smuggling attack also allows the attacker to poison that web cache and store arbitrary malicious content at any URL for delivery to other clients' future requests. This issue is fixed in version 7.6.
Weaknesses (CWE)
- CWE-444 — Inconsistent Interpretation of HTTP Requests
References
- https://github.com/squid-cache/squid/security/advisories/GHSA-537g-4gfh-w7m6
- https://github.com/squid-cache/squid/pull/2427
- https://github.com/squid-cache/squid/pull/2431
- https://github.com/squid-cache/squid/commit/d06f48de8b8cc9a378cb91ecfe8e89b6e81696d2
- https://github.com/squid-cache/squid/commit/d808a7c825a70275113790471135c9c4d547ee51
- https://github.com/squid-cache/squid/releases/tag/SQUID_7_6
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 7.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N | GitHub_M |
| CVSS 3.1 | HIGH 7.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N | NVD · security-advisories@github.com (Secondary) |
European references
- ENISA EUVD · EUVD-2026-98919
- GCVE · GCVE-0-2026-61642
CERT-FR advisories
- CERTFR-2026-AVI-1168 — Multiples vulnérabilités dans Squid · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| squid-cache · squid | affected >= 3.3.0.1, < 7.6 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |