CVE-2026-66338 | A flaw was found in libsoup. The chunked transfer encoding p… | CVSS 5.4 MEDIUM

Description

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.

Metadata

CVE ID: CVE-2026-66338
State: PUBLISHED
Assigner: redhat
Reserved: 2026-07-24 22:32 UTC
Published: 2026-07-24 23:01 UTC
Last updated: 2026-07-24 23:01 UTC
Primary CWE: CWE-444
Inconsistent Interpretation of HTTP Requests ('HTTP Request/…
Vendor / Product: Red Hat / Red Hat Enterprise Linux 10
Sources: cve.org · NVD

Severity & Metrics

5.4 MEDIUM CVSS 3.1

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

Affected products (5)

Vendor	Product	Platform	Versions
Red Hat	Red Hat Enterprise Linux 10	—	—
Red Hat	Red Hat Enterprise Linux 6	—	—
Red Hat	Red Hat Enterprise Linux 7	—	—
Red Hat	Red Hat Enterprise Linux 8	—	—
Red Hat	Red Hat Enterprise Linux 9	—	—

Weakness (CWE)

CWE	Source	Description
CWE-444	cna	Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CVSS scores (1)

Score	Severity	Version	Source	Vector
5.4	MEDIUM	3.1	cna	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N

References (2)