HTTP Request Smuggling Affecting libsoup3 package, versions <3.6.6-1+e12


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.25% (15th percentile)

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  • Snyk IDSNYK-ECHOLATEST-LIBSOUP3-20360704
  • published1 Oct 2026
  • disclosed30 Sept 2026

Introduced: 30 Sep 2026

NewCVE-2026-103399  (opens in a new tab)
CWE-444  (opens in a new tab)

How to fix?

Upgrade Echo:latest libsoup3 to version 3.6.6-1+e12 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libsoup3 package and not the libsoup3 package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1