Local kernel memory corruption via BPF verifier bypass
Published Sep 25, 2026 · Updated Sep 25, 2026
BPF verifier bypass in Linux 6.6.15 through 6.7 allows local users to corrupt kernel memory via a crafted bpf_loop program. During second-pass precision backtracking, backtrack_insn clears outer-frame R1-R5 after a callback BPF_EXIT, so a later bpf_loop checkpoint loses the precise loop count and the verifier accepts an unsafe out-of-bounds write. Loading the trigger requires permission to call bpf(); systems with unprivileged BPF disabled restrict that path to CAP_SYS_ADMIN or CAP_BPF.
Summary
What happened
BPF verifier bypass in Linux 6.6.15 through 6.7 allows local users to corrupt kernel memory via a crafted bpf_loop program. During second-pass precision backtracking, backtrack_insn clears outer-frame R1-R5 after a callback BPF_EXIT, so a later bpf_loop checkpoint loses the precise loop count and the verifier accepts an unsafe out-of-bounds write. Loading the trigger requires permission to call bpf(); systems with unprivileged BPF disabled restrict that path to CAP_SYS_ADMIN or CAP_BPF.
The record
- CVE
- CVE-2026-98084
- Published
- Sep 25, 2026
- Updated
- Sep 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1068
- 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=6.6.15 <6.7
- Affected versionversion=6.7
- Affected versionversion=ab5cfac139ab8576fb54630d4cca23c3e690ee90 <e3e4f66cc4b72333d0886ae2673c360248987889
- Affected versionversion=ab5cfac139ab8576fb54630d4cca23c3e690ee90 <f83890dfed9efc5e19df1dbc1ad707a142936923
- Affected versionversion=b43550d7d58e7ae6618aaab18c1e912fa4d6e3dd
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
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
Public exploit references
- Linux BPF unsafe bpf_loop checkpoint regression testproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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