Bug 2521357 (CVE-2026-74625)

Summary:	CVE-2026-74625 kernel: netfilter: bridge: release template ct on non-IP path
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
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 the Linux kernel's netfilter bridge component. This vulnerability allows for a memory leak when the system processes non-IPv4 and non-IPv6 network traffic through a bridge nftables connection tracking rule. The system fails to release an existing connection tracking template reference, leading to a gradual accumulation of unreleased memory. This can ultimately result in a denial of service (DoS) condition as the host runs out of available memory.	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:

Description OSIDB Bzimport 2026-08-22 15:41:33 UTC

In the Linux kernel, the following vulnerability has been resolved:

netfilter: bridge: release template ct on non-IP path

A bridge nftables ct zone set rule can attach a conntrack template to
an skb before nf_ct_bridge_pre() sees it. For non-IPv4 and non-IPv6
EtherTypes, nf_ct_bridge_pre() currently overwrites skb->_nfct with
IP_CT_UNTRACKED without releasing the existing template reference.

That makes the per-cpu template, and any temporary templates allocated
for concurrent use, unreachable and leaks memory until the host runs out
of slab.

Reset the skb conntrack state before marking the frame untracked so the
existing template reference is dropped on the non-IP path.

Comment 1 gkamathe 2026-08-24 06:44:47 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082220-CVE-2026-74625-e32d@gregkh/T