Bug 2500547

Summary: CVE-2026-15711 libsoup: libsoup: WebSocket remote denial of service via oversized control frame protocol violation [fedora-all]
Product: [Fedora] Fedora Reporter: Ganesh <gnaik>
Component: libsoupAssignee: Gwyn Ciesla <gwync>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: rawhideCC: gwync, mclasen, rhughes, rstrode, tpopela
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["92105fae-a4eb-42af-8c14-cd9455b3cbd9"]}
Fixed In Version: Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2499924    

Description Ganesh 2026-07-14 19:38:47 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

**Vulnerability Reference:**

A flaw in libsoup's WebSocket implementation allows a remote attacker to trigger a denial of service (DoS) by exploiting a protocol validation failure.

**Component / Vulnerable Part:**

`libsoup` -> `libsoup/websocket/soup-websocket-connection.c` (Control frame parser)

**Technical Analysis & Root Cause:**

Per RFC 6455 ยง5.5, WebSocket control frames (PING, PONG, CLOSE) must not exceed a payload length of 125 bytes and cannot be fragmented. libsoup's frame parsing logic fails to immediately reject non-compliant control frames exceeding this limit. When an oversized control frame is received, the unexpected state disrupts the state machine or triggers an unhandled execution error, forcing the library to abruptly crash.

**Impact:**

A remote, unauthenticated attacker (client or server) can send a single malformed, oversized control frame to instantly terminate the connection wrapper, resulting in a remote denial of service for any application using libsoup WebSockets.