HTTP Request Smuggling Affecting libsoup-devel package, versions <0:2.56.0-6.amzn2.0.9


Severity

Recommended
0.0
medium
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.29% (21st percentile)

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  • Snyk IDSNYK-AMZN2-LIBSOUPDEVEL-20847397
  • published13 Oct 2026
  • disclosed24 Jul 2026

Introduced: 24 Jul 2026

CVE-2026-66338  (opens in a new tab)
CWE-444  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2 libsoup-devel to version 0:2.56.0-6.amzn2.0.9 or higher.
This issue was patched in ALAS2-2026-3970.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libsoup-devel package and not the libsoup-devel package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1