Linux kernel XFRM use-after-free allows local privilege escalation
ZDI rates CVE-2026-98231 at CVSS 7.8; low-privileged local code execution is required first.
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CVE-2026-98231
Use-after-free in Linux kernel XFRM device state flush
- CVSS
- —
- EPSS
- —
- Published
- ·
- Modified
AI analysisSummaries by Vani AI
A race in the Linux kernel XFRM subsystem lets the deferred device-state flush and the state garbage collector free the same xfrm_state. A local process can hit it via device flag changes (devinet_ioctl) while XFRM states are being destroyed; both paths call the driver callback and drop the device reference, and one can use the state after it is freed. ZDI classifies this as local privilege escalation. Affected kernel builds are not listed.
What to do: Apply the Linux kernel update that serializes xfrm_state destruction against the deferred device pass for CVE-2026-98231. No fixed version or workaround is stated.
| Product | Affected |
|---|---|
| Linux kernel | — |
Estimated exposure
No basis for an estimate.
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description · NVD
In the Linux kernel, the following vulnerability has been resolved: xfrm: serialize state GC with device state flush The deferred-device pass in xfrm_dev_state_flush() finds states under xfrm_state_dev_gc_lock, but drops the lock before calling xfrm_dev_state_free() because the driver callback may sleep. The device GC list does not hold an xfrm_state reference, so the state GC worker can destroy the same state concurrently. The race can proceed as follows: CPU 0 CPU 1 find x on the device GC list drop xfrm_state_dev_gc_lock read x->xso.dev xfrm_state_gc_destroy(x) xfrm_dev_state_free(x) xfrm_state_free(x) continue xfrm_dev_state_free(x) Both paths can invoke the driver callback and drop the device reference. CPU 0 can also access the xfrm_state after CPU 1 has freed it. KASAN reported: BUG: KASAN: slab-use-after-free in xfrm_dev_state_free+0x24c/0x2a0 Read of size 8 at addr ffff88810bbaa960 by task poc/102 Call Trace: xfrm_dev_state_free+0x24c/0x2a0 xfrm_dev_state_flush+0x353/0x400 xfrm_dev_event+0x26d/0x3a0 notifier_call_chain+0xc0/0x280 __dev_notify_flags+0x169/0x250 netif_change_flags+0xe7/0x160 dev_change_flags+0x96/0x220 devinet_ioctl+0x7f4/0x1880 Allocated by task 87: xfrm_state_alloc+0x1e/0x5c0 xfrm_add_sa+0xe7f/0x5820 xfrm_user_rcv_msg+0x4f3/0x940 Freed by task 57: kmem_cache_free+0xcb/0x3d0 xfrm_state_gc_task+0x4a8/0x650 process_one_work+0x63a/0x1070 Serialize xfrm_state destruction against the deferred-device pass with a mutex. Keep xfrm_state_dev_gc_lock limited to list operations and retain the existing callback and device-reference release ordering.