CVE-2026-61642
Squid Request Smuggling in HTTP Transfer-Encoding
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High7.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N |
| NVDNVD · Awaiting Analysis | 3.1 | High7.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 2.0% · top 19% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.7.
Weakness
Affected products
- affected >= 3.3.0.1, < 7.6
References (6)
- https://github.com/squid-cache/squid/security/advisories/GHSA-537g-4gfh-w7m6 (opens in a new tab)x_refsource_CONFIRM
- https://github.com/squid-cache/squid/pull/2427 (opens in a new tab)x_refsource_MISC
- https://github.com/squid-cache/squid/pull/2431 (opens in a new tab)x_refsource_MISC
- https://github.com/squid-cache/squid/commit/d06f48de8b8cc9a378cb91ecfe8e89b6e81696d2 (opens in a new tab)x_refsource_MISC
- https://github.com/squid-cache/squid/commit/d808a7c825a70275113790471135c9c4d547ee51 (opens in a new tab)x_refsource_MISC
- https://github.com/squid-cache/squid/releases/tag/SQUID_7_6 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-61642)Record last updated .