Vulnerability in Red Hat Enterprise Linux 10
CVE-2026-103399
A flaw was found in SoupServer (libsoup). When an HTTP/1.x client sends a request with Expect: 100-continue and a request body, and SoupServer returns an early final (non-1xx) response before the body is read, the server neither drains the declared body bytes nor closes the connection. On a keep-alive connection, those leftover bytes are interpreted as a subsequent HTTP request. A remote, unauthenticated attacker can place a complete HTTP request in the body and cause SoupServer to process that smuggled request, leading to unintended request handling.
Vulnerability class: HTTP Request Smuggling
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- access.redhat.com/security/cve/CVE-2026-103399 (vdb-entry)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking)
Frequently asked questions
- What is CVE-2026-103399?
- CVE-2026-103399 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 5.3/10. Published 2026-09-30.
- How severe is CVE-2026-103399?
- Medium severity. CVSS v3 base score is 5.3 out of 10.