CVE intelligence

CVE-2026-66338

Vulnerability intelligence

Published Jul 24, 2026Sources checked Sep 12, 2026

7.2HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-66338 and is rated High severity with a CVSS score of 7.2. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.2%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is 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.