{"id":"CVE-2025-38169","state":"PUBLISHED","title":"arm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP","description":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP\n\nOn system with SME, a thread's kernel FPSIMD state may be erroneously\nclobbered during a context switch immediately after that state is\nrestored. Systems without SME are unaffected.\n\nIf the CPU happens to be in streaming SVE mode before a context switch\nto a thread with kernel FPSIMD state, fpsimd_thread_switch() will\nrestore the kernel FPSIMD state using fpsimd_load_kernel_state() while\nthe CPU is still in streaming SVE mode. When fpsimd_thread_switch()\nsubsequently calls fpsimd_flush_cpu_state(), this will execute an\nSMSTOP, causing an exit from streaming SVE mode. The exit from\nstreaming SVE mode will cause the hardware to reset a number of\nFPSIMD/SVE/SME registers, clobbering the FPSIMD state.\n\nFix this by calling fpsimd_flush_cpu_state() before restoring the kernel\nFPSIMD state.","publishedAt":"2025-07-03T08:36:08.393Z","updatedAt":"2026-10-15T21:52:10.436Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e92bee9f861b466c676f0200be3e46af7bc4ac6b","status":"affected","lessThan":"55d52af498daea75aa03ba9b7e444c8ae495ac20","versionType":"git"},{"version":"e92bee9f861b466c676f0200be3e46af7bc4ac6b","status":"affected","lessThan":"a305821f597ec943849d3e53924adb88c61ed682","versionType":"git"},{"version":"e92bee9f861b466c676f0200be3e46af7bc4ac6b","status":"affected","lessThan":"01098d893fa8a6edb2b56e178b798e3e6b674f02","versionType":"git"},{"version":"e003c485ac82a9f8de4204912ed059ac6dd4257c","status":"affected","versionType":"git"},{"version":"25b90cd122d546823da90b916f7c3289dfe83a99","status":"affected","versionType":"git"},{"version":"6.8.12","status":"affected","lessThan":"6.9","versionType":"semver"},{"version":"6.9.3","status":"affected","lessThan":"6.10","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kernel/fpsimd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.10","versionType":"semver"},{"version":"6.12.34","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.15.3","status":"unaffected","lessThanOrEqual":"6.15.*","versionType":"semver"},{"version":"6.16","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kernel/fpsimd.c"]}],"references":["https://git.kernel.org/stable/c/55d52af498daea75aa03ba9b7e444c8ae495ac20","https://git.kernel.org/stable/c/a305821f597ec943849d3e53924adb88c61ed682","https://git.kernel.org/stable/c/01098d893fa8a6edb2b56e178b798e3e6b674f02"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/38xxx/CVE-2025-38169.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-38169","state":"PUBLISHED","datePublished":"2025-07-03T08:36:08.393Z","dateUpdated":"2026-10-15T21:52:10.436Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T04:51:23.991Z"},"containers":{"cna":{"title":"arm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP\n\nOn system with SME, a thread's kernel FPSIMD state may be erroneously\nclobbered during a context switch immediately after that state is\nrestored. Systems without SME are unaffected.\n\nIf the CPU happens to be in streaming SVE mode before a context switch\nto a thread with kernel FPSIMD state, fpsimd_thread_switch() will\nrestore the kernel FPSIMD state using fpsimd_load_kernel_state() while\nthe CPU is still in streaming SVE mode. When fpsimd_thread_switch()\nsubsequently calls fpsimd_flush_cpu_state(), this will execute an\nSMSTOP, causing an exit from streaming SVE mode. The exit from\nstreaming SVE mode will cause the hardware to reset a number of\nFPSIMD/SVE/SME registers, clobbering the FPSIMD state.\n\nFix this by calling fpsimd_flush_cpu_state() before restoring the kernel\nFPSIMD state."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e92bee9f861b466c676f0200be3e46af7bc4ac6b","status":"affected","lessThan":"55d52af498daea75aa03ba9b7e444c8ae495ac20","versionType":"git"},{"version":"e92bee9f861b466c676f0200be3e46af7bc4ac6b","status":"affected","lessThan":"a305821f597ec943849d3e53924adb88c61ed682","versionType":"git"},{"version":"e92bee9f861b466c676f0200be3e46af7bc4ac6b","status":"affected","lessThan":"01098d893fa8a6edb2b56e178b798e3e6b674f02","versionType":"git"},{"version":"e003c485ac82a9f8de4204912ed059ac6dd4257c","status":"affected","versionType":"git"},{"version":"25b90cd122d546823da90b916f7c3289dfe83a99","status":"affected","versionType":"git"},{"version":"6.8.12","status":"affected","lessThan":"6.9","versionType":"semver"},{"version":"6.9.3","status":"affected","lessThan":"6.10","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kernel/fpsimd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.10","versionType":"semver"},{"version":"6.12.34","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.15.3","status":"unaffected","lessThanOrEqual":"6.15.*","versionType":"semver"},{"version":"6.16","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kernel/fpsimd.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/55d52af498daea75aa03ba9b7e444c8ae495ac20"},{"url":"https://git.kernel.org/stable/c/a305821f597ec943849d3e53924adb88c61ed682"},{"url":"https://git.kernel.org/stable/c/01098d893fa8a6edb2b56e178b798e3e6b674f02"}],"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 - Triggering requires executing SMSTART/streaming-SVE instructions at EL0 on the affected CPU and generating local scheduler pressure, so the attacker must be able to run code on the target. A remote peer cannot place the CPU into streaming SVE mode.\nAC:L - The attacker controls both sides of the race — they create the streaming-mode task and the kernel-mode NEON workload (AF_ALG, dm-crypt/fscrypt I/O, kTLS), and can pin both to one CPU via sched_setaffinity so ordinary tick preemption reproduces the clobber on demand. No memory layout or victim state outside the attacker's influence is needed, and CONFIG_ARM64_SME is default y.\nPR:L - do_sme_acc() enables SME and streaming mode for any EL0 task with no capability, namespace, or sysctl gate, and driving kernel-mode NEON via AF_ALG or plain I/O on an encrypted/checksummed filesystem needs no privilege. Only unprivileged local code execution is required.\nUI:N - The attacker's own tasks supply both the streaming-mode context and the preempted kernel NEON section; no victim action is needed, and any concurrent crypto/RAID work on the system is silently corrupted.\nS:U - The corruption is confined to kernel FPSIMD register state managed by the same kernel security authority; KVM already flushes and SMSTOPs guest FP state in kvm_arch_vcpu_put_fp(), so no guest/host or IOMMU boundary is crossed.\nC:H - Zeroing V0-V31 mid-operation destroys the in-register AES round-key schedule and IV (aes-ce.S load_round_keys/cbciv) or the ChaCha20 state, so the affected blocks are emitted under a known all-zero key — a fixed, invertible transform. An attacker who observes the resulting dm-crypt/fscrypt blocks or IPsec/kTLS/WireGuard packets recovers the plaintext that encryption was supposed to protect.\nI:H - Kernel crypto, hash, CRC and RAID6 computations silently return wrong results that are written to disk and the wire, corrupting encrypted volumes, RAID parity, filesystem checksums and dm-verity/dm-integrity data. A zeroed GHASH key also yields predictable authentication tags, enabling forgery against integrity-protected data.\nA:H - The silent miscomputation propagates into dm-verity/dm-integrity/filesystem checksum verification failures, producing I/O errors, forced read-only remounts, errors=panic aborts and Android restart-on-corruption reboots, plus unrecoverable RAID6 parity loss. The attacker can trigger it repeatedly and indefinitely."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:00:02.043Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"6.12.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"6.15.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"6.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2025-38169","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-15T21:48:10.598358Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-15T21:52:10.436Z"}}]}}}