CVE-2026-61642: squid · HTTP Request/Response Smuggling
Affects squidSource CVE Database V5
Not known to be exploited · CVSS 7.7 High : upgrade to 7.6 soon.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 2.2% chance of exploitation in 30 days – higher than 82% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-10-13.
- Patch
- Available – fixed in 7.6
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 13 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade squid to 7.6.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| squid-cachesquid | Affected
| Fixed in
|
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.
References
- github.com/squid-cache/squid/security/advisories/GHSA-537g-4gfh-w7m6 (opens in a new tab)
- github.com/squid-cache/squid/pull/2427 (opens in a new tab)
- github.com/squid-cache/squid/pull/2431 (opens in a new tab)
- github.com/squid-cache/squid/commit/d06f48de8b8cc9a378cb91ecfe8e89b6e81696d2 (opens in a new tab)
- github.com/squid-cache/squid/commit/d808a7c825a70275113790471135c9c4d547ee51 (opens in a new tab)
- github.com/squid-cache/squid/releases/tag/SQUID_7_6 (opens in a new tab)