Description
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).
Published: 2026-07-14
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

A flaw in libsoup’s WebSocket permessage‑deflate extension causes the inflate() buffer. When a remote, unauthenticated attacker sends a highly compressed payload, the library allocates unbounded memory, resulting in an Out‑of‑Memory crash that disables the service. This vulnerability represents an uncontrolled resource consumption409) and leads to denial of service to affected applications.

Affected Systems

The issue impacts Red Hat Enterprise Linux 6, 7, 8, 9, and 10, as they ship the vulnerable libsoup package. Any running libsoup that accept WebSocket connections on these operating systems are therefore susceptible.

Risk and Exploitability

The CVSS score of 7.5 indicates moderate severity. The EPSS score of < 1% reflects that exploitation is considered unlikely at present. No listing in the KEV catalog suggests no known active exploits. The likely attack vector is inferred to be remote, requiring the attacker to send a crafted WebSocket frame over an open network connection to a vulnerable service. The CNA states that no official workaround is available, and the vulnerability remains exploitable because the safe‑size check is disabled by default for client connections.

Generated by OpenCVE AI on July 31, 2026 at 05:24 UTC.

Remediation

Vendor Workaround

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.


OpenCVE Recommended Actions

  • Apply the Red Hat update that contains the patched libsoup package with the corrected permessage‑deflate handling.
  • Restrict the memory available to affected services (for example, by setting ulimitd mitigate the impact of a potential OOM crash.
  • Monitor WebSocket traffic and system memory for anomalous spikes, and review logs for evidence of attempted decompression bombs.

Generated by OpenCVE AI on July 31, 2026 at 05:24 UTC.

Tracking

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Advisories

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History

Wed, 15 Jul 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 15 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Tue, 14 Jul 2026 20:00:00 +0000

Type Values Removed Values Added
Description 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).
Title Soupwebsocketextensiondeflate: libsoup: libsoup: websocket permessage-deflate unbounded decompression remote denial of service
First Time appeared Redhat
Redhat enterprise Linux
Weaknesses CWE-409
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Subscriptions

Redhat Enterprise Linux
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-07-15T12:58:18.795Z

Reserved: 2026-07-14T09:32:47.038Z

Link: CVE-2026-15709

cve-icon Vulnrichment

Updated: 2026-07-15T12:57:37.820Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-07-14T09:42:00Z

Links: CVE-2026-15709 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-31T05:30:07Z

Weaknesses
  • CWE-409

    Improper Handling of Highly Compressed Data (Data Amplification)