Improper Handling of Highly Compressed Data (Data Amplification) Affecting libsoup-devel package, versions <0:2.72.0-16.el9_8.3


Severity

Recommended
medium

Based on AlmaLinux security rating.

Threat Intelligence

EPSS
0.88% (58th percentile)

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  • Snyk IDSNYK-ALMALINUX9-LIBSOUPDEVEL-19900329
  • published18 Sept 2026
  • disclosed16 Sept 2026

Introduced: 16 Sep 2026

CVE-2026-15709  (opens in a new tab)
CWE-409  (opens in a new tab)

How to fix?

Upgrade AlmaLinux:9 libsoup-devel to version 0:2.72.0-16.el9_8.3 or higher.
This issue was patched in ALSA-2026:68234.

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 AlmaLinux. See How to fix? for AlmaLinux:9 relevant fixed versions and status.

A flaw was found in libsoup's WebSocket implementation when using the permessage-deflate extension. The extension's decompression loop (inflate()) processes data in chunks without enforcing an upper boundary limit on the output buffer size. While libsoup limits the incoming compressed frame size via max_incoming_payload_size, it fails to track or limit memory allocation during decompression. A separate check for decompressed size (max_total_message_size) exists but executes only after inflation is complete, and it is entirely disabled by default for client connections. A remote, unauthenticated attacker can exploit this by sending a small, highly compressed payload (a decompression bomb), causing unbounded memory allocation that triggers an Out-of-Memory (OOM) crash and a Denial of Service (DoS).

CVSS Base Scores

version 3.1