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CVE-2026-98047

Linux: bpf: Check ancestor frames for rbtree callbacks

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.18%Chance of exploitation activity in the next 30 days, higher than 7% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in252e9b476af723edd299a5c71c389ec018e46656Also 2410cb2ac0416dd2795a81984c8c73d7250bd8c4, 369f4ce734570bdfedaa4b5ca50e2a3f6a892728CVE List
Published25 Sep 2026Updated 21 Oct 2026CVE List

What fixes it

  • 252e9b476af723edd299a5c71c389ec018e46656LinuxCVE List
  • 2410cb2ac0416dd2795a81984c8c73d7250bd8c4LinuxCVE List
  • 369f4ce734570bdfedaa4b5ca50e2a3f6a892728LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

In the Linux kernel, the following vulnerability has been resolved:

bpf: Check ancestor frames for rbtree callbacks

bpf_rbtree_add() invokes its comparator while the caller holds the root lock. The native insertion code retains raw parent and link pointers across the callback, so the verifier prohibits unlocking, consuming tree nodes, or changing RCU state from that callback.

in_rbtree_lock_required_cb() only checks the innermost verifier frame. Static subprogram calls are permitted while holding a spin lock, and such a call pushes a frame without in_callback_fn set. Consequently, all callback restrictions disappear in the nested frame. The subprogram can unlock the tree, remove and drop the node being compared, then relock. Native insertion resumes with the stale parent pointer and links freed memory into the tree.

Walk all active frames for the rbtree callback instead. Benign static subprograms remain permitted, while callback restrictions follow execution into nested frames.

Text from CVE List

Affected versions 10

  • Linuxaffected: a44b1334aadd82203f661adb9adb41e53ad0e8d1 before 252e9b476af723edd299a5c71c389ec018e46656CVE List
  • Linuxaffected: a44b1334aadd82203f661adb9adb41e53ad0e8d1 before b545fa447e09e6844868deb2bee228827fe54d15CVE List
  • Linuxaffected: a44b1334aadd82203f661adb9adb41e53ad0e8d1 before 2410cb2ac0416dd2795a81984c8c73d7250bd8c4CVE List
  • Linuxaffected: a44b1334aadd82203f661adb9adb41e53ad0e8d1 before 369f4ce734570bdfedaa4b5ca50e2a3f6a892728CVE List
  • Linuxaffected: 6.9CVE List
  • Linuxunaffected: all versions before 6.9CVE List
  • Linuxunaffected: 6.12.114 through 6.12.*CVE List
  • Linuxunaffected: 6.18.53 through 6.18.*CVE List
  • Linuxunaffected: 7.2.7 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 4