Local privilege escalation via stale reply length
Published Dec 29, 2024 · Updated Aug 5, 2026
Out-of-bounds write in the Linux kernel 6.12 allows local users to gain kernel privileges through NFSv3 LOCALIO reads after RPC fallback. The nfs_local_read_done function leaves res.replen uninitialized, and later NFSv3 request setup treats that stale value as a reply-header length, directing sock_recvmsg data outside the intended RPC buffer. Exploitation requires an accessible LOCALIO-enabled NFS mount and a transition back to normal RPC; the corruption discloses kernel memory, alters kernel state, or crashes the host.
Summary
What happened
Out-of-bounds write in the Linux kernel 6.12 allows local users to gain kernel privileges through NFSv3 LOCALIO reads after RPC fallback. The nfs_local_read_done function leaves res.replen uninitialized, and later NFSv3 request setup treats that stale value as a reply-header length, directing sock_recvmsg data outside the intended RPC buffer. Exploitation requires an accessible LOCALIO-enabled NFS mount and a transition back to normal RPC; the corruption discloses kernel memory, alters kernel state, or crashes the host.
The record
- CVE
- CVE-2024-56740
- Published
- Dec 29, 2024
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-787, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Dec 29, 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=6.12
- Affected versionversion=70ba381e1a431245c137ed597ec6a05991c79bd9 <650703bc4ed3edf841e851c99ab8e7ba9e5262a3
- Affected versionversion=70ba381e1a431245c137ed597ec6a05991c79bd9 <de5dac261eeab99762bbdf7c20cee5d26ef4462e
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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