Bug 2562676 (CVE-2026-99167)

Summary: CVE-2026-99167 kernel: net/sched: fix use-after-free in __tcf_action_put()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the Linux kernel's traffic control (net/sched) subsystem. Due to improper synchronization in the __tcf_action_put() function, reference and binding counts are updated out of sequence during action cleanup, allowing memory to be released while still being accessed. A local attacker could exploit this race condition to cause a use-after-free error, potentially resulting in local privilege escalation or a Denial of Service (DoS) via a system crash.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-10-28 10:48:03 UTC 
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.
Comment 1 gkamathe 2026-10-28 19:03:42 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-99167.mbox