{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-37964", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:23.974Z", "datePublished": "2025-05-20T16:01:56.013Z", "dateUpdated": "2026-08-05T11:58:41.507Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:58:41.507Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/mm: Eliminate window where TLB flushes may be inadvertently skipped\n\ntl;dr: There is a window in the mm switching code where the new CR3 is\nset and the CPU should be getting TLB flushes for the new mm. But\nshould_flush_tlb() has a bug and suppresses the flush. Fix it by\nwidening the window where should_flush_tlb() sends an IPI.\n\nLong Version:\n\n=== History ===\n\nThere were a few things leading up to this.\n\nFirst, updating mm_cpumask() was observed to be too expensive, so it was\nmade lazier. But being lazy caused too many unnecessary IPIs to CPUs\ndue to the now-lazy mm_cpumask(). So code was added to cull\nmm_cpumask() periodically[2]. But that culling was a bit too aggressive\nand skipped sending TLB flushes to CPUs that need them. So here we are\nagain.\n\n=== Problem ===\n\nThe too-aggressive code in should_flush_tlb() strikes in this window:\n\n\t// Turn on IPIs for this CPU/mm combination, but only\n\t// if should_flush_tlb() agrees:\n\tcpumask_set_cpu(cpu, mm_cpumask(next));\n\n\tnext_tlb_gen = atomic64_read(&next->context.tlb_gen);\n\tchoose_new_asid(next, next_tlb_gen, &new_asid, &need_flush);\n\tload_new_mm_cr3(need_flush);\n\t// ^ After 'need_flush' is set to false, IPIs *MUST*\n\t// be sent to this CPU and not be ignored.\n\n this_cpu_write(cpu_tlbstate.loaded_mm, next);\n\t// ^ Not until this point does should_flush_tlb()\n\t// become true!\n\nshould_flush_tlb() will suppress TLB flushes between load_new_mm_cr3()\nand writing to 'loaded_mm', which is a window where they should not be\nsuppressed. Whoops.\n\n=== Solution ===\n\nThankfully, the fuzzy \"just about to write CR3\" window is already marked\nwith loaded_mm==LOADED_MM_SWITCHING. Simply checking for that state in\nshould_flush_tlb() is sufficient to ensure that the CPU is targeted with\nan IPI.\n\nThis will cause more TLB flush IPIs. But the window is relatively small\nand I do not expect this to cause any kind of measurable performance\nimpact.\n\nUpdate the comment where LOADED_MM_SWITCHING is written since it grew\nyet another user.\n\nPeter Z also raised a concern that should_flush_tlb() might not observe\n'loaded_mm' and 'is_lazy' in the same order that switch_mm_irqs_off()\nwrites them. Add a barrier to ensure that they are observed in the\norder they are written." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The race is driven entirely through local syscalls (`madvise(MADV_DONTNEED)`/`mprotect`/`munmap` plus thread creation and CPU affinity) combined with scheduler-driven `switch_mm_irqs_off()` transitions; there is no network-reachable path into `arch/x86/mm/tlb.c`.\nAC:L - The attacker controls both sides of the race — one pinned thread loops TLB-flushing operations on a shared mm while other threads force repeated context switches into that mm on another CPU — and can retry millions of times per second; the window spans the CR3 write, and the bug was observed triggering under ordinary production workloads without adversarial tuning.\nPR:L - Every ingredient (multithreaded process, `madvise`/`mprotect` on its own anonymous memory, `sched_setaffinity`, `sched_yield`) is available to any unprivileged local user with no capabilities and no namespace tricks required.\nUI:N - The attacking process triggers the missed flush entirely on its own; no victim action, mount, or file open is involved.\nS:U - The stale TLB entry and the resulting memory corruption are both within the kernel/OS security authority; no hypervisor, IOMMU, or sandbox boundary is crossed as defined by CVSS scope.\nC:H - A suppressed flush leaves a live user mapping to a physical page the kernel has already freed and reallocated, allowing the attacker to read page-cache contents, other processes' anonymous memory, or kernel data placed in that page — effectively arbitrary memory disclosure.\nI:H - The retained mapping is writable, so the attacker can write into reallocated pages including page tables and kernel slab objects, yielding an arbitrary-write primitive and privilege escalation; missed flushes after COW/KSM write-protect additionally allow writing pages now shared with other processes.\nA:H - Writes through stale entries into recycled kernel page tables and slab objects corrupt kernel state, producing oopses and panics — the class of corruption that prompted the original production bug report." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/x86/mm/tlb.c" ], "versions": [ { "version": "848b5815177582de0e1d0118725378e0fbadca20", "lessThan": "12f703811af043d32b1c8a30001b2fa04d5cd0ac", "status": "affected", "versionType": "git" }, { "version": "b47002ed65ade940839b7f439ff4a194e7d5ec28", "lessThan": "02ad4ce144bd27f71f583f667fdf3b3ba0753477", "status": "affected", "versionType": "git" }, { "version": "a04fe3bfc71e28009e20357b79df1e8ef7c9d600", "lessThan": "d41072906abec8bb8e01ed16afefbaa558908c89", "status": "affected", "versionType": "git" }, { "version": "3dbe889a1b829b4c07e0836ff853fe649e51ce4f", "lessThan": "d87392094f96e162fa5fa5a8640d70cc0952806f", "status": "affected", "versionType": "git" }, { "version": "6db2526c1d694c91c6e05e2f186c085e9460f202", "lessThan": "399ec9ca8fc4999e676ff89a90184ec40031cf59", "status": "affected", "versionType": "git" }, { "version": "6db2526c1d694c91c6e05e2f186c085e9460f202", "lessThan": "fea4e317f9e7e1f449ce90dedc27a2d2a95bee5a", "status": "affected", "versionType": "git" }, { "version": "d1347977661342cb09a304a17701eb2d4aa21dec", "status": "affected", "versionType": "git" }, { "version": "5.15.179", "lessThan": "5.15.183", "status": "affected", "versionType": "semver" }, { "version": "6.1.129", "lessThan": "6.1.139", "status": "affected", "versionType": "semver" }, { "version": "6.6.79", "lessThan": "6.6.91", "status": "affected", "versionType": "semver" }, { "version": "6.12.16", "lessThan": "6.12.29", "status": "affected", "versionType": "semver" }, { "version": "6.13.4", "lessThan": "6.14", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/x86/mm/tlb.c" ], "versions": [ { "version": "6.14", "status": "affected" }, { "version": "0", "lessThan": "6.14", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.183", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.139", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.91", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.29", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.14.7", "lessThanOrEqual": "6.14.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.15", "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": "5.15.179", "versionEndExcluding": "5.15.183" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.129", "versionEndExcluding": "6.1.139" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.79", "versionEndExcluding": "6.6.91" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.16", "versionEndExcluding": "6.12.29" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "6.14.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "6.15" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13.4" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/12f703811af043d32b1c8a30001b2fa04d5cd0ac" }, { "url": "https://git.kernel.org/stable/c/02ad4ce144bd27f71f583f667fdf3b3ba0753477" }, { "url": "https://git.kernel.org/stable/c/d41072906abec8bb8e01ed16afefbaa558908c89" }, { "url": "https://git.kernel.org/stable/c/d87392094f96e162fa5fa5a8640d70cc0952806f" }, { "url": "https://git.kernel.org/stable/c/399ec9ca8fc4999e676ff89a90184ec40031cf59" }, { "url": "https://git.kernel.org/stable/c/fea4e317f9e7e1f449ce90dedc27a2d2a95bee5a" } ], "title": "x86/mm: Eliminate window where TLB flushes may be inadvertently skipped", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:57:49.771Z" } }, { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:41:16.660Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" } ], "references": [ { "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html" } ] } ] } }