CVE-2024-56721

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there is no remote or adjacent input path, and the resulting misbehaviour is only observable to software running locally on the affected AMD Zen1/Zen2 machine.\nAC:L - On any family 0x17 CPU whose model/stepping does not match the two table entries, `x86_match_cpu_with_stepping()` runs past the array end on every single boot \u2014 deterministic, no race to win and no special preconditions.\nPR:L - The faulty walk executes automatically during CPU identification before any authentication exists, and observing or leveraging the consequences (skipped XSAVES erratum workaround, corrupted XMM state) needs only ordinary unprivileged local access; matches the CNA scoring of the identical bug in CVE-2025-37751.\nUI:N - The out-of-bounds walk happens automatically as part of boot-time CPU feature initialization and CPU hotplug; no victim action of any kind is involved.\nS:U - The out-of-bounds read and its consequences are entirely contained within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The loop performs an unbounded out-of-bounds read of whatever kernel `.rodata` follows `erratum_1386_microcode[]`, with no upper limit on how far it reads, and that out-of-bounds data is then consumed as CPU descriptor/microcode-revision values; additionally, wrongly skipping the erratum 1386 workaround leaves XSAVES able to expose stale XMM register contents across context switches.\nI:N - The defect is a read-only over-read \u2014 nothing is written outside the array bounds and no attacker-controlled data is stored \u2014 matching the I:N assigned to the identical `erratum_1386_microcode` terminator bug (CVE-2025-37751).\nA:H - The walk continues arbitrarily far past the array until it randomly encounters an entry with zero family and model, so depending on linker layout it can fault or trip UBSAN/KASAN and oops during early boot \u2014 exactly the boot-time crash seen with the analogous missing-sentinel errata arrays (CVE-2025-37929)."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/x86/kernel/cpu/amd.c"], "versions": [{"version": "29ba89f1895285f06c333546882e0c5ae9a6df23", "lessThan": "82d6b82cf89d950982ac240ba068c3a7e1f23b0a", "status": "affected", "versionType": "git"}, {"version": "29ba89f1895285f06c333546882e0c5ae9a6df23", "lessThan": "ccfee14f08b8699132b87bc6d78e0fa75bf094dd", "status": "affected", "versionType": "git"}, {"version": "29ba89f1895285f06c333546882e0c5ae9a6df23", "lessThan": "ff6cdc407f4179748f4673c39b0921503199a0ad", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/x86/kernel/cpu/amd.c"], "versions": [{"version": "6.10", "status": "affected"}, {"version": "0", "lessThan": "6.10", "status": "unaffected", "versionType": "semver"}, {"version": "6.11.11", "lessThanOrEqual": "6.11.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.2", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.13", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.11.11"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.12.2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.13"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/82d6b82cf89d950982ac240ba068c3a7e1f23b0a"}, {"url": "https://git.kernel.org/stable/c/ccfee14f08b8699132b87bc6d78e0fa75bf094dd"}, {"url": "https://git.kernel.org/stable/c/ff6cdc407f4179748f4673c39b0921503199a0ad"}], "title": "x86/CPU/AMD: Terminate the erratum_1386_microcode array", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.1, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"id": "CVE-2024-56721", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2025-10-01T19:58:17.697625Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-125", "description": "CWE-125 Out-of-bounds Read"}]}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-10-01T20:07:05.975Z"}}]}}

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there is no remote or adjacent input path, and the resulting misbehaviour is only observable to software running locally on the affected AMD Zen1/Zen2 machine.\nAC:L - On any family 0x17 CPU whose model/stepping does not match the two table entries, `x86_match_cpu_with_stepping()` runs past the array end on every single boot \u2014 deterministic, no race to win and no special preconditions.\nPR:L - The faulty walk executes automatically during CPU identification before any authentication exists, and observing or leveraging the consequences (skipped XSAVES erratum workaround, corrupted XMM state) needs only ordinary unprivileged local access; matches the CNA scoring of the identical bug in CVE-2025-37751.\nUI:N - The out-of-bounds walk happens automatically as part of boot-time CPU feature initialization and CPU hotplug; no victim action of any kind is involved.\nS:U - The out-of-bounds read and its consequences are entirely contained within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The loop performs an unbounded out-of-bounds read of whatever kernel `.rodata` follows `erratum_1386_microcode[]`, with no upper limit on how far it reads, and that out-of-bounds data is then consumed as CPU descriptor/microcode-revision values; additionally, wrongly skipping the erratum 1386 workaround leaves XSAVES able to expose stale XMM register contents across context switches.\nI:N - The defect is a read-only over-read \u2014 nothing is written outside the array bounds and no attacker-controlled data is stored \u2014 matching the I:N assigned to the identical `erratum_1386_microcode` terminator bug (CVE-2025-37751).\nA:H - The walk continues arbitrarily far past the array until it randomly encounters an entry with zero family and model, so depending on linker layout it can fault or trip UBSAN/KASAN and oops during early boot \u2014 exactly the boot-time crash seen with the analogous missing-sentinel errata arrays (CVE-2025-37929)."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "29ba89f1895285f06c333546882e0c5ae9a6df23", "lessThan": "82d6b82cf89d950982ac240ba068c3a7e1f23b0a", "versionType": "git"}, {"status": "affected", "version": "29ba89f1895285f06c333546882e0c5ae9a6df23", "lessThan": "ccfee14f08b8699132b87bc6d78e0fa75bf094dd", "versionType": "git"}, {"status": "affected", "version": "29ba89f1895285f06c333546882e0c5ae9a6df23", "lessThan": "ff6cdc407f4179748f4673c39b0921503199a0ad", "versionType": "git"}], "programFiles": ["arch/x86/kernel/cpu/amd.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "6.10"}, {"status": "unaffected", "version": "0", "lessThan": "6.10", "versionType": "semver"}, {"status": "unaffected", "version": "6.11.11", "versionType": "semver", "lessThanOrEqual": "6.11.*"}, {"status": "unaffected", "version": "6.12.2", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.13", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["arch/x86/kernel/cpu/amd.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/82d6b82cf89d950982ac240ba068c3a7e1f23b0a"}, {"url": "https://git.kernel.org/stable/c/ccfee14f08b8699132b87bc6d78e0fa75bf094dd"}, {"url": "https://git.kernel.org/stable/c/ff6cdc407f4179748f4673c39b0921503199a0ad"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/CPU/AMD: Terminate the erratum_1386_microcode array\n\nThe erratum_1386_microcode array requires an empty entry at the end.\nOtherwise x86_match_cpu_with_stepping() will continue iterate the array after\nit ended.\n\nAdd an empty entry to erratum_1386_microcode to its end."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.11.11", "versionStartIncluding": "6.10"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.2", "versionStartIncluding": "6.10"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.13", "versionStartIncluding": "6.10"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:46:19.207Z"}}}, "cveMetadata": {"cveId": "CVE-2024-56721", "state": "PUBLISHED", "dateUpdated": "2026-08-05T11:46:19.207Z", "dateReserved": "2024-12-27T15:00:39.858Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2024-12-29T11:29:59.164Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

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{"bugzilla": {"description": "kernel: x86/CPU/AMD: Terminate the erratum_1386_microcode array", "id": "2334820", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2334820"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H", "status": "draft"}, "cwe": "CWE-125", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nx86/CPU/AMD: Terminate the erratum_1386_microcode array\nThe erratum_1386_microcode array requires an empty entry at the end.\nOtherwise x86_match_cpu_with_stepping() will continue iterate the array after\nit ended.\nAdd an empty entry to erratum_1386_microcode to its end.", "A flaw was found in the AMD CPU erratum handling code in the Linux kernel. The erratum_1386_microcode array lacked a proper terminator, which could cause the x86_match_cpu_with_stepping() function to read beyond the end of the array. This results in undefined behavior during CPU feature detection and erratum handling. A local attacker may be able to exploit this flaw to cause a system crash or instability, affecting system availability."], "name": "CVE-2024-56721", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2024-12-29T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2024-56721\nhttps://nvd.nist.gov/vuln/detail/CVE-2024-56721\nhttps://lore.kernel.org/linux-cve-announce/2024122922-CVE-2024-56721-aaac@gregkh/T"], "threat_severity": "Moderate"}

{}