{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2025-21991", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-21991", "idYear": 2025, "status": "PUBLISHED", "publishedAt": "2025-04-02T12:53:14.230Z", "updatedAt": "2026-05-23T15:57:34.986Z", "importedAt": "2026-10-24T01:57:29.455Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes\n\nCurrently, load_microcode_amd() iterates over all NUMA nodes, retrieves their\nCPU masks and unconditionally accesses per-CPU data for the first CPU of each\nmask.\n\nAccording to Documentation/admin-guide/mm/numaperf.rst:\n\n \"Some memory may share the same node as a CPU, and others are provided as\n memory only nodes.\"\n\nTherefore, some node CPU masks may be empty and wouldn't have a \"first CPU\".\n\nOn a machine with far memory (and therefore CPU-less NUMA nodes):\n- cpumask_of_node(nid) is 0\n- cpumask_first(0) is CONFIG_NR_CPUS\n- cpu_data(CONFIG_NR_CPUS) accesses the cpu_info per-CPU array at an\n index that is 1 out of bounds\n\nThis does not have any security implications since flashing microcode is\na privileged operation but I believe this has reliability implications by\npotentially corrupting memory while flashing a microcode update.\n\nWhen booting with CONFIG_UBSAN_BOUNDS=y on an AMD machine that flashes\na microcode update. I get the following splat:\n\n UBSAN: array-index-out-of-bounds in arch/x86/kernel/cpu/microcode/amd.c:X:Y\n index 512 is out of range for type 'unsigned long[512]'\n [...]\n Call Trace:\n dump_stack\n __ubsan_handle_out_of_bounds\n load_microcode_amd\n request_microcode_amd\n reload_store\n kernfs_fop_write_iter\n vfs_write\n ksys_write\n do_syscall_64\n entry_SYSCALL_64_after_hwframe\n\nChange the loop to go over only NUMA nodes which have CPUs before determining\nwhether the first CPU on the respective node needs microcode update.\n\n [ bp: Massage commit message, fix typo. ]", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "979e197968a1e8f09bf0d706801dba4432f85ab3", "status": "affected", "versionType": "git", "lessThan": "d509c4731090ebd9bbdb72c70a2d70003ae81f4f" }, { "version": "44a44b57e88f311c1415be1f567c50050913c149", "status": "affected", "versionType": "git", "lessThan": "985a536e04bbfffb1770df43c6470f635a6b1073" }, { "version": "be2710deaed3ab1402379a2ede30a3754fe6767a", "status": "affected", "versionType": "git", "lessThan": "18b5d857c6496b78ead2fd10001b81ae32d30cac" }, { "version": "d576547f489c935b9897d4acf8beee3325dea8a5", "status": "affected", "versionType": "git", "lessThan": "ec52240622c4d218d0240079b7c1d3ec2328a9f4" }, { "version": "7ff6edf4fef38ab404ee7861f257e28eaaeed35f", "status": "affected", "versionType": "git", "lessThan": "e686349cc19e800dac8971929089ba5ff59abfb0" }, { "version": "7ff6edf4fef38ab404ee7861f257e28eaaeed35f", "status": "affected", "versionType": "git", "lessThan": "488ffc0cac38f203979f83634236ee53251ce593" }, { "version": "7ff6edf4fef38ab404ee7861f257e28eaaeed35f", "status": "affected", "versionType": "git", "lessThan": "5ac295dfccb5b015493f86694fa13a0dde4d3665" }, { "version": "7ff6edf4fef38ab404ee7861f257e28eaaeed35f", "status": "affected", "versionType": "git", "lessThan": "e3e89178a9f4a80092578af3ff3c8478f9187d59" }, { "version": "d6353e2fc12c5b8f00f86efa30ed73d2da2f77be", "status": "affected", "versionType": "git" }, { "version": "1b1e0eb1d2971a686b9f7bdc146115bcefcbb960", "status": "affected", "versionType": "git" }, { "version": "eaf5dea1eb8c2928554b3ca717575cbe232b843c", "status": "affected", "versionType": "git" }, { "version": "5.4.235", "status": "affected", "versionType": "semver", "lessThan": "5.4.292" }, { "version": "5.10.173", "status": "affected", "versionType": "semver", "lessThan": "5.10.236" }, { "version": "5.15.99", "status": "affected", "versionType": "semver", "lessThan": "5.15.180" }, { "version": "6.1.16", "status": "affected", "versionType": "semver", "lessThan": "6.1.132" }, { "version": "4.14.308", "status": "affected", "versionType": "semver", "lessThan": "4.15" }, { "version": "4.19.276", "status": "affected", "versionType": "semver", "lessThan": "4.20" }, { "version": "6.2.3", "status": "affected", "versionType": "semver", "lessThan": "6.3" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "6.3", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "6.3" }, { "version": "5.4.292", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.4.*" }, { "version": "5.10.236", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.180", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.132", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.84", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.20", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.13.8", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.13.*" }, { "version": "6.14", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }