Squid Request Smuggling in HTTP Transfer-Encoding

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-61642
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-13 17:17:42 UTC
Updated2026-10-16 16:00:33 UTC
DescriptionSquid 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.

Risk And Classification

Primary CVSS: v3.1 7.7 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N

Problem Types: CWE-444 | CWE-444 CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.7HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N
3.1CNADECLARED7.7HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Squid-cache Squid affected >= 3.3.0.1, < 7.6 Not specified

References

ReferenceSourceLinkTags
github.com/squid-cache/squid/commit/d06f48de8b8cc9a378cb91ecfe8e89b6e816... [email protected] github.com
github.com/squid-cache/squid/pull/2431 [email protected] github.com
github.com/squid-cache/squid/releases/tag/SQUID_7_6 [email protected] github.com
github.com/squid-cache/squid/security/advisories/GHSA-537g-4gfh-w7m6 [email protected] github.com
github.com/squid-cache/squid/pull/2427 [email protected] github.com
github.com/squid-cache/squid/commit/d808a7c825a70275113790471135c9c4d547... [email protected] github.com
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