Memory corruption via CPU-less NUMA index
Published Apr 2, 2025 · Updated May 23, 2026
Out-of-bounds access in Linux kernel AMD microcode loading allows local administrators to corrupt memory during a microcode update. load_microcode_amd() selects the first CPU from every NUMA node mask and passes CONFIG_NR_CPUS to cpu_data() when a CPU-less node has an empty mask. Reachability requires an AMD system with CPU-less NUMA nodes and root or CAP_SYS_ADMIN access to trigger microcode reloading.
Summary
What happened
Out-of-bounds access in Linux kernel AMD microcode loading allows local administrators to corrupt memory during a microcode update. load_microcode_amd() selects the first CPU from every NUMA node mask and passes CONFIG_NR_CPUS to cpu_data() when a CPU-less node has an empty mask. Reachability requires an AMD system with CPU-less NUMA nodes and root or CAP_SYS_ADMIN access to trigger microcode reloading.
The record
- CVE
- CVE-2025-21991
- Published
- Apr 2, 2025
- Updated
- May 23, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-129
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Apr 2, 2025CVE publishedPublication date reported by the CVE source.
- May 23, 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=1b1e0eb1d2971a686b9f7bdc146115bcefcbb960
- Affected versionversion=4.14.308 <4.15
- Affected versionversion=4.19.276 <4.20
- Affected versionversion=44a44b57e88f311c1415be1f567c50050913c149 <985a536e04bbfffb1770df43c6470f635a6b1073
- Affected versionversion=5.10.173 <5.10.236
- Affected versionversion=5.15.99 <5.15.180
- Affected versionversion=5.4.235 <5.4.292
- Affected versionversion=6.1.16 <6.1.132
- Affected versionversion=6.2.3 <6.3
- Affected versionversion=6.3
- Affected versionversion=7ff6edf4fef38ab404ee7861f257e28eaaeed35f <488ffc0cac38f203979f83634236ee53251ce593
- Affected versionversion=7ff6edf4fef38ab404ee7861f257e28eaaeed35f <5ac295dfccb5b015493f86694fa13a0dde4d3665
- Affected versionversion=7ff6edf4fef38ab404ee7861f257e28eaaeed35f <e3e89178a9f4a80092578af3ff3c8478f9187d59
- Affected versionversion=7ff6edf4fef38ab404ee7861f257e28eaaeed35f <e686349cc19e800dac8971929089ba5ff59abfb0
- Affected versionversion=979e197968a1e8f09bf0d706801dba4432f85ab3 <d509c4731090ebd9bbdb72c70a2d70003ae81f4f
- Affected versionversion=be2710deaed3ab1402379a2ede30a3754fe6767a <18b5d857c6496b78ead2fd10001b81ae32d30cac
- Affected versionversion=d576547f489c935b9897d4acf8beee3325dea8a5 <ec52240622c4d218d0240079b7c1d3ec2328a9f4
- Affected versionversion=d6353e2fc12c5b8f00f86efa30ed73d2da2f77be
- Affected versionversion=eaf5dea1eb8c2928554b3ca717575cbe232b843c
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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