System hang via misclassified BPF atomics
Published May 21, 2024 · Updated Aug 5, 2026
Improper BPF handling in Linux 5.12 before 5.12.19 and 5.13 before 5.13.4 allows local users to hang PowerPC64 systems. In bpf_jit_build_body, the acceptance check reads the first instruction's immediate field instead of the current instruction's field, so unsupported BPF_FETCH atomics are emitted as plain additions. A local user able to load a crafted BPF socket-filter program can trigger the mismatch and soft-lock the host; remote traffic alone cannot reach it.
Summary
What happened
Improper BPF handling in Linux 5.12 before 5.12.19 and 5.13 before 5.13.4 allows local users to hang PowerPC64 systems. In bpf_jit_build_body, the acceptance check reads the first instruction's immediate field instead of the current instruction's field, so unsupported BPF_FETCH atomics are emitted as plain additions. A local user able to load a crafted BPF socket-filter program can trigger the mismatch and soft-lock the host; remote traffic alone cannot reach it.
The record
- CVE
- CVE-2021-47317
- Published
- May 21, 2024
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-667, T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- May 21, 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=5.12
- Affected versionversion=91c960b0056672e74627776655c926388350fa30 <0d435b6d94b05dcfd836d758a63145aa566618e2
- Affected versionversion=91c960b0056672e74627776655c926388350fa30 <419ac821766cbdb9fd85872bb3f1a589df05c94c
- Affected versionversion=91c960b0056672e74627776655c926388350fa30 <7284dab07e4d51d453cc42851fae9ec4fac6ef2f
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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