CVE-2026-66338

A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid characters. When libsoup operates behind a strict frontend proxy, this parsing differential can be exploited to smuggle HTTP requests.

CVSS v3 5.4 MEDIUM

5.4^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://access.redhat.com/security/cve/CVE-2026-66338	Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2506950	Exploit Issue Tracking Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:gnome:libsoup:-:::::::*
	cpe:2.3:o:redhat:enterprise_linux:6.0:::::::*
	cpe:2.3:o:redhat:enterprise_linux:7.0:::::::*
	cpe:2.3:o:redhat:enterprise_linux:8.0:::::::*
	cpe:2.3:o:redhat:enterprise_linux:9.0:::::::*
	cpe:2.3:o:redhat:enterprise_linux:10.0:::::::*

History

No history.

Information

Published : 2026-07-24 23:16

Updated : 2026-08-24 16:44

NVD link : CVE-2026-66338

Mitre link : CVE-2026-66338

CVE.ORG link : CVE-2026-66338

JSON object : View

Products Affected

redhat

enterprise_linux

gnome

libsoup

CWE

CWE-444

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

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