Kernel panic via negative BPF ALU offset
Published Nov 12, 2025 · Updated Aug 5, 2026
Improper input validation in affected Linux kernel releases allows local users to panic the kernel through a malformed BPF ALU instruction. The check_alu_op() verifier test applies only an upper-bound comparison to a signed 16-bit offset, so negative values bypass the zero-or-one restriction for division and modulo operations. Local access plus unprivileged BPF or delegated CAP_BPF is required; x86 execution can panic the system, while s390 execution can disclose kernel register data.
Summary
What happened
Improper input validation in affected Linux kernel releases allows local users to panic the kernel through a malformed BPF ALU instruction. The check_alu_op() verifier test applies only an upper-bound comparison to a signed 16-bit offset, so negative values bypass the zero-or-one restriction for division and modulo operations. Local access plus unprivileged BPF or delegated CAP_BPF is required; x86 execution can panic the system, while s390 execution can disclose kernel register data.
The record
- CVE
- CVE-2025-40169
- Published
- Nov 12, 2025
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Nov 12, 2025CVE publishedPublication date reported by the CVE source.
- Aug 5, 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
- Affected versionversion=ec0e2da95f72d4a46050a4d994e4fe471474fd80 <21167bf70dbe400563e189ac632258d35eda38b5
- Affected versionversion=ec0e2da95f72d4a46050a4d994e4fe471474fd80 <3bce44b344040e5eef3d64d38b157c15304c0aab
- Affected versionversion=ec0e2da95f72d4a46050a4d994e4fe471474fd80 <5017c302ca4b2a45149ad64e058fa2d5623c068f
- Affected versionversion=ec0e2da95f72d4a46050a4d994e4fe471474fd80 <55c0ced59fe17dee34e9dfd5f7be63cbab207758
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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