Bug 2502412 (CVE-2026-63919)

Summary: CVE-2026-63919 kernel: xfrm: input: hold netns during deferred transport reinjection
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's xfrm input component. The transport-mode reinjection process, which handles network packet re-injection, stores a network namespace pointer that must remain valid until a deferred callback completes. However, a missing reference count for the network namespace during this deferred operation could lead to a use-after-free vulnerability. This could allow an attacker to potentially cause a system crash or other unpredictable behavior if the network namespace is deallocated prematurely.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-07-19 16:06:47 UTC 
In the Linux kernel, the following vulnerability has been resolved:

xfrm: input: hold netns during deferred transport reinjection

Transport-mode reinjection stores a struct net pointer in skb->cb and
uses it later from xfrm_trans_reinject(). That pointer must stay valid
until the deferred callback runs.

Take a netns reference when queueing deferred reinjection work and drop
it after the callback completes. Use maybe_get_net() so the queueing
path does not revive a namespace that is already being torn down.

This keeps the existing workqueue design and fixes the netns lifetime
handling in one place for all users of xfrm_trans_queue_net().
Comment 1 Keith Grant 2026-07-21 21:15:13 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071947-CVE-2026-63919-e224@gregkh/T