VulnerabilityPublished 25 Sep 2026Updated 21 Oct 2026

CVE-2026-98047: Linux kernel · bpf: Check ancestor frames for rbtree callbacks

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in b545fa447e09e6844868deb2bee228827fe54d15 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 17:30 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in b545fa447e09e6844868deb2bee228827fe54d15, 2410cb2ac0416dd2795a81984c8c73d7250bd8c4, 369f4ce734570bdfedaa4b5ca50e2a3f6a892728 +1

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to b545fa447e09e6844868deb2bee228827fe54d15, 2410cb2ac0416dd2795a81984c8c73d7250bd8c4, 369f4ce734570bdfedaa4b5ca50e2a3f6a892728 or 252e9b476af723edd299a5c71c389ec018e46656.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ a44b1334aadd82203f661adb9adb41e53ad0e8d1, < b545fa447e09e6844868deb2bee228827fe54d15	Fixed in b545fa447e09e6844868deb2bee228827fe54d15
LinuxLinux	Affected ≥ a44b1334aadd82203f661adb9adb41e53ad0e8d1, < 2410cb2ac0416dd2795a81984c8c73d7250bd8c4	Fixed in 2410cb2ac0416dd2795a81984c8c73d7250bd8c4
LinuxLinux	Affected ≥ a44b1334aadd82203f661adb9adb41e53ad0e8d1, < 369f4ce734570bdfedaa4b5ca50e2a3f6a892728	Fixed in 369f4ce734570bdfedaa4b5ca50e2a3f6a892728
LinuxLinux	Affected ≥ a44b1334aadd82203f661adb9adb41e53ad0e8d1, < 252e9b476af723edd299a5c71c389ec018e46656	Fixed in 252e9b476af723edd299a5c71c389ec018e46656
LinuxLinux	Affected =6.9	Fixed in–

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.

References

Community reviews

Loading reviews…