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7.8
Linux kernel can reference a network device after it’s removed
published 6 months ago
Summary
A component that processes encrypted network packets in the Linux kernel could try to use a network interface after the interface has been taken down, leading to possible crashes or instability. The fix changes the timing of when the kernel releases its hold on the interface, ensuring it is only released after packet handling is fully complete. Apply the latest kernel updates that contain this correction to keep the system stable.
What to do
- Update linux kernel to version 6.19.13.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| Linux | linux | kernel |
>= 6.19.0, < 6.19.13 Fix: upgrade to 6.19.13
|
Original advisory text
xfrm: hold dev ref until after transport_finish NF_HOOK
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.
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.
References
- https://git.kernel.org/stable/c/0f451b43c88bf2b9c038b414be580efee42e031b URL
- https://git.kernel.org/stable/c/1c428b03840094410c5fb6a5db30640486bbbfcb URL
- https://git.kernel.org/stable/c/4236c30b437b80f673b9e08c8fae38b8d471ac9e URL
- https://git.kernel.org/stable/c/5002beda5cac69d522dc54da0d5d463ed9c963d2 URL
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31663.json URL
- https://access.redhat.com/security/cve/CVE-2026-31663 Vendor Advisory
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31663... Vendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-31663 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2461462 Third Party Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git Product
Internet-facing
14 days
Internal
At next upgrade
- Not known to be exploited
- Needs hands-on effort to exploit (estimated)
- Gives an attacker full control (estimated)
Timeline
Published24 Apr 2026
Updated25 Aug 2026
First seen25 Aug 2026
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