Request Smuggling Vulnerability in SoupServer by Red Hat
CVE-2026-103399

5.3MEDIUM

Key Information:

Vendor

Red Hat
Status
Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Vendor
CVE Published:
30 September 2026

What is CVE-2026-103399?

A flaw in SoupServer (libsoup) allows a remote, unauthenticated attacker to exploit a vulnerability when an HTTP/1.x client sends a request with Expect: 100-continue. If SoupServer responds prematurely and the request body is not fully read, the server fails to drain or close the connection, potentially leading to the server incorrectly processing a smuggled HTTP request. This can result in unintended behavior, including the mishandling of requests, which poses significant security concerns.

References

https://access.redhat.com/security/cve/CVE-2026-103399
vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2543949
issue-trackingx_refsource_REDHAT

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Red Hat would like to thank Jianqiang (Stark) Li for reporting this issue.
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