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CVE-2026-15709

Soupwebsocketextensiondeflate: libsoup: libsoup: websocket permessage-deflate unbounded decompression remote denial of service

publishedCWE-409

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).

Technical severity7.5 highCVSS 3.1 · CNA: redhat
Published2026-07-14Source updated 2026-11-05
Collected2026-11-053 attributed sources

Fixes and workarounds

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.

Source: CNA: redhat

Affected products and versions

ProductVersionsAuthority
Red Hat Enterprise Linux 10
Red Hat
libsoup3
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:3.6.5-3.el10_2.14; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 10.0 Extended Update Support
Red Hat
libsoup3
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:3.6.5-3.el10_0.17; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:2.62.3-2.el8_4.10; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:2.62.3-2.el8_4.10; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:2.62.3-2.el8_6.10; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:2.62.3-2.el8_6.10; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 8.8 Telecommunications Update Service
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:2.62.3-3.el8_8.11; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:2.62.3-3.el8_8.11; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 9
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:2.72.0-16.el9_8.3; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:2.72.0-8.el9_2.13; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:2.72.0-8.el9_4.12; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 9.6 Extended Update Support
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:2.72.0-10.el9_6.9; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 6
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: unknown 		CNA: redhat
Red Hat Enterprise Linux 7
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: unknown 		CNA: redhat
Red Hat Enterprise Linux 8
Red Hat
libsoup
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: affected 		CNA: redhat

Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.

CVSS assessments

Version / scoreVectorAuthority
3.1 / 7.5
high		 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCNA: redhat
3.1 / 7.5
high		 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HNVD: [email protected]

Exploit evidence

References

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