Bug 2461462 (CVE-2026-31663)

Summary: CVE-2026-31663 kernel: xfrm: hold dev ref until after transport_finish NF_HOOK
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: 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 `xfrm` (IP eXtensible FRamework) subsystem. This vulnerability involves a race condition where a network device's reference is released too early during packet processing after asynchronous cryptography. This premature release can lead to the system attempting to access a deallocated device, potentially causing a system crash (Denial of Service).
 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 2026-04-24 15:02:51 UTC 
In the Linux kernel, the following vulnerability has been resolved:

xfrm: hold dev ref until after transport_finish NF_HOOK

After async crypto completes, xfrm_input_resume() calls dev_put()
immediately on re-entry before the skb reaches transport_finish.
The skb->dev pointer is then used inside NF_HOOK and its okfn,
which can race with device teardown.

Remove the dev_put from the async resumption entry and instead
drop the reference after the NF_HOOK call in transport_finish,
using a saved device pointer since NF_HOOK may consume the skb.
This covers NF_DROP, NF_QUEUE and NF_STOLEN paths that skip
the okfn.

For non-transport exits (decaps, gro, drop) and secondary
async return points, release the reference inline when
async is set.
Comment 1 Keith Grant 2026-04-24 22:22:14 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042404-CVE-2026-31663-164c@gregkh/T