CVE-2026-66338
MEDIUMLibsoup: libsoup: http request smuggling via permissive chunk-size parsing in soup_body_input_stream_read_chunked()
Title source: cnaDescription
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.
References (2)
Core 2
Core References
Vdb Entry, X_Refsource_Redhat vdb-entry
x_refsource_redhat
https://access.redhat.com/security/cve/CVE-2026-66338
Issue Tracking, X_Refsource_Redhat issue-tracking
x_refsource_redhat
RHBZ#2506950
https://bugzilla.redhat.com/show_bug.cgi?id=2506950
Scores
CVSS v3
5.4
EPSS
0.0017
EPSS Percentile
7.0%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
partial
Details
CWE
CWE-444
Status
published
Products (5)
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
Published
Jul 24, 2026
Tracked Since
Jul 25, 2026