Kernel memory corruption via nested rbtree callback
Published Sep 25, 2026 · Updated Sep 25, 2026
Use-after-free in the BPF verifier in Linux 6.9 allows local users to corrupt kernel memory through a crafted rbtree callback. The in_rbtree_lock_required_cb() check inspects only the innermost verifier frame, so a static subprogram loses callback restrictions and can free a compared node while native insertion retains its parent and link pointers. Reachability requires the ability to load BPF programs and a comparator that unlocks the tree, removes and drops the node, and relocks it before insertion resumes.
Summary
What happened
Use-after-free in the BPF verifier in Linux 6.9 allows local users to corrupt kernel memory through a crafted rbtree callback. The in_rbtree_lock_required_cb() check inspects only the innermost verifier frame, so a static subprogram loses callback restrictions and can free a compared node while native insertion retains its parent and link pointers. Reachability requires the ability to load BPF programs and a comparator that unlocks the tree, removes and drops the node, and relocks it before insertion resumes.
The record
- CVE
- CVE-2026-98047
- Published
- Sep 25, 2026
- Updated
- Sep 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Sep 25, 2026CVE publishedPublication date reported by the CVE source.
- Sep 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=6.9
- Affected versionversion=a44b1334aadd82203f661adb9adb41e53ad0e8d1 <2410cb2ac0416dd2795a81984c8c73d7250bd8c4
- Affected versionversion=a44b1334aadd82203f661adb9adb41e53ad0e8d1 <369f4ce734570bdfedaa4b5ca50e2a3f6a892728
- Affected versionversion=a44b1334aadd82203f661adb9adb41e53ad0e8d1 <b545fa447e09e6844868deb2bee228827fe54d15
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
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Technologies
Your stack
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Your stack
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