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CVE-2026-103399

Libsoup: soupserver: http/1 request smuggling via undrained expect: 100-continue body

Published
Last modified
published
Not listed in CISA KEV
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • libsoup3

    Version range not reported

  • libsoup

    Version range not reported

  • libsoup

    Version range not reported

  • libsoup

    Version range not reported

  • libsoup

    Version range not reported

References 2

access.redhat.com

bugzilla.redhat.com