CVE-2026-15711: Libsoup: soupwebsocketconnection: libsoup: websocket remote denial of service via oversized control frame protocol violation

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-14 · updated 2026-09-24
Weakness: CWE-770

Description

A vulnerability was found in libsoup's WebSocket frame parsing implementation. The library fails to validate length rules specified in RFC 6455 §5.5, which mandates that all WebSocket control frames (e.g., PING, PONG, CLOSE) contain a payload of 125 bytes or less. A remote, unauthenticated attacker can exploit this by sending a non-compliant, oversized control frame. Because the parser handles this protocol violation improperly instead of throwing an immediate connection termination error, it triggers a internal processing crash, resulting in a remote denial of service (DoS) for applications utilizing libsoup WebSockets.

Affected products

Red Hat Enterprise Linux 10: all versions — fixed in 0:3.6.5-3.el10_2.14
Red Hat Enterprise Linux 10.0 Extended Update Support: all versions — fixed in 0:3.6.5-3.el10_0.17
Red Hat Enterprise Linux 8: all versions — fixed in 0:2.62.3-15.el8_10
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support: all versions — fixed in 0:2.62.3-2.el8_4.10
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On: all versions — fixed in 0:2.62.3-2.el8_4.10
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support: all versions — fixed in 0:2.62.3-2.el8_6.10
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On: all versions — fixed in 0:2.62.3-2.el8_6.10
Red Hat Enterprise Linux 8.8 Telecommunications Update Service: all versions — fixed in 0:2.62.3-3.el8_8.11
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions: all versions — fixed in 0:2.62.3-3.el8_8.11
Red Hat Enterprise Linux 9: all versions — fixed in 0:2.72.0-16.el9_8.3
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions: all versions — fixed in 0:2.72.0-8.el9_2.13
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions: all versions — fixed in 0:2.72.0-8.el9_4.12
Red Hat Enterprise Linux 9.6 Extended Update Support: all versions — fixed in 0:2.72.0-10.el9_6.9

How to fix

Upgrade to a fixed version: Red Hat Enterprise Linux 10 0:3.6.5-3.el10_2.14; Red Hat Enterprise Linux 10.0 Extended Update Support 0:3.6.5-3.el10_0.17; Red Hat Enterprise Linux 8 0:2.62.3-15.el8_10; Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:2.62.3-2.el8_4.10; Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:2.62.3-2.el8_4.10; Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:2.62.3-2.el8_6.10; Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On 0:2.62.3-2.el8_6.10; Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:2.62.3-3.el8_8.11; Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:2.62.3-3.el8_8.11; Red Hat Enterprise Linux 9 0:2.72.0-16.el9_8.3; Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:2.72.0-8.el9_2.13; Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions 0:2.72.0-8.el9_4.12. Check the vendor advisory for mitigations.

References

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