Bug 2489980 (CVE-2026-12151)

Summary:	CVE-2026-12151 undici: undici: Denial of Service due to unbounded memory growth via WebSocket frames
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:	aazores, abarbaro, alizardo, ataylor, cdrage, cmah, dbruscin, dschmidt, eaguilar, ebaron, erezende, jchui, jhe, jkoehler, jlanda, jolong, kaycoth, kshier, ktsao, kvanderr, lphiri, manissin, nboldt, oaljalju, pjindal, psrna, rhel-process-autobot, rushinde, sdawley, simaishi, smcdonal, stcannon, teagle, watson-tool-maintainers, yguenane
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in undici. A malicious WebSocket server can exploit this by streaming numerous small or empty continuation frames. This can bypass per-frame and cumulative-size validation, leading to unbounded memory growth in the client process. The primary consequence is memory exhaustion, resulting in a denial of service (DoS) for affected applications using the undici WebSocket client or WebSocketStream API.	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:	2490221, 2490224, 2490225, 2490226, 2490223
Bug Blocks:

Description OSIDB Bzimport 2026-06-17 17:02:07 UTC

Impact:
The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service.

Affected applications are those using the undici WebSocket client (new WebSocket(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.

All releases starting at undici 6.17.0 are affected.

Patches: Upgrade to undici >= 6.26.0, >= 7.28.0, or >= 8.5.0. Workarounds:
No workaround is available. The fix must be applied through an upgrade.