Kernel crash via unlocked sockmap callback read
Published May 30, 2024 · Updated May 11, 2026
NULL pointer dereference in the Linux kernel allows local users to crash the system through concurrent BPF sockmap activity. The sk_psock_data_ready helper reads saved_data_ready without sk_callback_lock while sk_psock_drop can clear that pointer under the lock, creating a race that dereferences NULL. Triggering requires local access to exercise BPF sockmap verdict handling while a mapped socket closes; the documented consequence is a kernel crash.
Summary
What happened
NULL pointer dereference in the Linux kernel allows local users to crash the system through concurrent BPF sockmap activity. The sk_psock_data_ready helper reads saved_data_ready without sk_callback_lock while sk_psock_drop can clear that pointer under the lock, creating a race that dereferences NULL. Triggering requires local access to exercise BPF sockmap verdict handling while a mapped socket closes; the documented consequence is a kernel crash.
The record
- CVE
- CVE-2024-36938
- Published
- May 30, 2024
- Updated
- May 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- May 30, 2024CVE publishedPublication date reported by the CVE source.
- May 11, 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=4.20
- Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <39dc9e1442385d6e9be0b6491ee488dddd55ae27
- Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <5965bc7535fb87510b724e5465ccc1a1cf00916d
- Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <6648e613226e18897231ab5e42ffc29e63fa3365
- Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <772d5729b5ff0df0d37b32db600ce635b2172f80
- Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <b397a0ab8582c533ec0c6b732392f141fc364f87
- Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <c0809c128dad4c3413818384eb06a341633db973
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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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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