Out-of-bounds kernel access via mispredicted JMP32 branch
Published Sep 25, 2026 · Updated Sep 25, 2026
Out-of-bounds access in the Linux BPF verifier allows local users to load unsafe BPF programs through crafted JMP32 comparisons. The is_branch_taken() helper treats a 32-bit pointer-versus-zero comparison like a full-width comparison, predicts the branch as always taken, and skips verification of the fall-through path. Reaching the flaw requires permission to load BPF programs; an accepted fall-through path can perform an out-of-bounds map-value access in kernel context.
Summary
What happened
Out-of-bounds access in the Linux BPF verifier allows local users to load unsafe BPF programs through crafted JMP32 comparisons. The is_branch_taken() helper treats a 32-bit pointer-versus-zero comparison like a full-width comparison, predicts the branch as always taken, and skips verification of the fall-through path. Reaching the flaw requires permission to load BPF programs; an accepted fall-through path can perform an out-of-bounds map-value access in kernel context.
The record
- CVE
- CVE-2026-98041
- 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?
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- Affected versionversion=5.8
- Affected versionversion=cac616db39c207dc63465a4e05c6ce0e60b2cce4 <a4d7f94c1ca914469ced665ec2f98be669aef462
- Affected versionversion=cac616db39c207dc63465a4e05c6ce0e60b2cce4 <d16f0eafcaa62e677a2b5b0dabc1f8d31dfe3d4d
- Affected versionversion=cac616db39c207dc63465a4e05c6ce0e60b2cce4 <e2ae33247e8b2dbe9d116d3e61cadf6d548339c6
- Affected versionversion=cac616db39c207dc63465a4e05c6ce0e60b2cce4 <e51179a4e09846f8fd0f26a05068520de2b301bf
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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