Service interruption via negative shift exponent
Published Feb 27, 2025 · Updated May 11, 2026
Shift-out-of-bounds in Linux kernel 6.12 allows local users to disrupt operation through mlx5 hardware steering. The HWS_SET32 macro in the mlx5 HWS definer left-shifts a value by a signed field offset without handling negative offsets, producing undefined behavior and a UBSAN fault. Exploitation requires local access and execution of the affected hardware-steering path; published evidence establishes availability impact but not data access or code execution.
Summary
What happened
Shift-out-of-bounds in Linux kernel 6.12 allows local users to disrupt operation through mlx5 hardware steering. The HWS_SET32 macro in the mlx5 HWS definer left-shifts a value by a signed field offset without handling negative offsets, producing undefined behavior and a UBSAN fault. Exploitation requires local access and execution of the affected hardware-steering path; published evidence establishes availability impact but not data access or code execution.
The record
- CVE
- CVE-2025-21800
- Published
- Feb 27, 2025
- Updated
- May 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 27, 2025CVE 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=6.12
- Affected versionversion=74a778b4a63faef9ff02aad0d332b209835f93e1 <69c676c0ded472713e6d1b3a456b3c4f52f66f0e
- Affected versionversion=74a778b4a63faef9ff02aad0d332b209835f93e1 <92cff996624c4757d5bbace3dfa3f1567ba94143
- Affected versionversion=74a778b4a63faef9ff02aad0d332b209835f93e1 <be482f1d10da781db9445d2753c1e3f1fd82babf
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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