CVE-2026-66338 — Libsoup: libsoup: http request smuggling via permissive chunk-size parsing in soup_body_input_stream_read_chunked()

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
Red Hat / Red Hat Enterprise Linux 10	affected
Red Hat / Red Hat Enterprise Linux 6	affected
Red Hat / Red Hat Enterprise Linux 7	affected
Red Hat / Red Hat Enterprise Linux 8	affected
Red Hat / Red Hat Enterprise Linux 9	affected

CWE

CWE-444

References

https://access.redhat.com/security/cve/CVE-2026-66338
https://bugzilla.redhat.com/show_bug.cgi?id=2506950

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.