Linux kernel UAF in __tcf_action_put() from misordered ref and bind counts
CVE-2026-99167 Published on October 28, 2026
net/sched: fix use-after-free in __tcf_action_put()
In the Linux kernel, the following vulnerability has been resolved:
net/sched: fix use-after-free in __tcf_action_put()
__tcf_action_put() decrements the reference count before decrementing the
binding count. Another thread can free the action between these operations,
causing the binding-count update to access freed memory. KASAN reports it
as:
BUG: KASAN: slab-use-after-free in __tcf_action_put+0x327/0x340
Write of size 4 at addr ff11000000d46420 by task tc-put-pause/64
Hold the action IDR mutex across both counter updates and IDR removal,
keeping cleanup outside the lock.
Products Associated with CVE-2026-99167
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Affected Versions
Linux:- Version 16af6067392c40e454e49eec834843ab03643d96 and below 2465d27ef90de9105c2bffb6c35f8ce08918e642 is affected.
- Version 16af6067392c40e454e49eec834843ab03643d96 and below 2e012e431aa271ef3c84206f48854f539c03bff0 is affected.
- Version 16af6067392c40e454e49eec834843ab03643d96 and below 7b16eb911091aae237a8673da94e4dfb9cd21d54 is affected.
- Version 4.19 is affected.
- Before 4.19 is unaffected.
- Version 6.18.59, <= 6.18.* is unaffected.
- Version 7.2.13, <= 7.2.* is unaffected.
- Version 7.3, <= * is unaffected.