Kernel-memory disclosure and crash via verifier flag
Published Feb 27, 2024 · Updated Aug 5, 2026
Improper input validation in the Linux kernel BPF verifier allows local users to crash the system or disclose kernel memory. In adjust_ptr_min_max_vals(), the verifier checks mixed-signed scalar bounds against allow_ptr_leaks instead of bypass_spec_v1, incorrectly permitting pointer arithmetic that Spectre v1 masking requires it to reject. Local low-privileged access and permission to submit BPF programs are required; the documented consequences are limited to kernel-memory disclosure and a system crash.
Summary
What happened
Improper input validation in the Linux kernel BPF verifier allows local users to crash the system or disclose kernel memory. In adjust_ptr_min_max_vals(), the verifier checks mixed-signed scalar bounds against allow_ptr_leaks instead of bypass_spec_v1, incorrectly permitting pointer arithmetic that Spectre v1 masking requires it to reject. Local low-privileged access and permission to submit BPF programs are required; the documented consequences are limited to kernel-memory disclosure and a system crash.
The record
- CVE
- CVE-2021-46908
- Published
- Feb 27, 2024
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 27, 2024CVE 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=2c78ee898d8f10ae6fb2fa23a3fbaec96b1b7366 <4ccdc6c6cae38b91c871293fb0ed8c6845a61b51
- Affected versionversion=2c78ee898d8f10ae6fb2fa23a3fbaec96b1b7366 <4f3ff11204eac0ee23acf64deecb3bad7b0db0c6
- Affected versionversion=2c78ee898d8f10ae6fb2fa23a3fbaec96b1b7366 <9601148392520e2e134936e76788fc2a6371e7be
- Affected versionversion=5.8
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What is affected?
Published CVSS scores
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Attacks
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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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