Bug 2543229 (CVE-2026-102556)

Summary:	CVE-2026-102556 libsoup: libsoup: Heap buffer overflow from WebSocket Pong signal type confusion
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in libsoup. When handling an incoming WebSocket Pong frame, SoupWebsocketConnection emitted the ::pong signal with a GByteArray pointer even though the signal is declared to pass a GBytes. Applications connecting a handler that follows the documented GBytes API can trigger heap corruption or a crash upon receiving a crafted Pong.	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:	2543264, 2543266, 2543267
Bug Blocks:

Description OSIDB Bzimport 2026-09-29 14:53:18 UTC

A type-confusion heap overflow was found in libsoup's WebSocket Pong handling.

SoupWebsocketConnection::pong is declared to deliver a GBytes payload, but receive_pong() emitted a GByteArray pointer via g_signal_emit() and then unreffed the GByteArray. Handlers that treated the argument as GBytes (as documented) operated on the wrong object layout, resulting in heap memory corruption / overflow conditions under ASan.

Fixed upstream by converting the buffer with g_byte_array_free_to_bytes() before emission (commit d2cbaf25, libsoup 3.7.3).

References:
https://gitlab.gnome.org/GNOME/libsoup/-/work_items/554 (Bug 2)
https://gitlab.gnome.org/GNOME/libsoup/-/commit/d2cbaf25