{"cve":"CVE-2025-38689","nvd":{"published":"2025-09-04T16:15:37.013","modified":"2026-10-19T21:10:00.160","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nx86/fpu: Fix NULL dereference in avx512_status()\n\nProblem\n-------\nWith CONFIG_X86_DEBUG_FPU enabled, reading /proc/[kthread]/arch_status\ncauses a warning and a NULL pointer dereference.\n\nThis is because the AVX-512 timestamp code uses x86_task_fpu() but\ndoesn't check it for NULL. CONFIG_X86_DEBUG_FPU addles that function\nfor kernel threads (PF_KTHREAD specifically), making it return NULL.\n\nThe point of the warning was to ensure that kernel threads only access\ntask->fpu after going through kernel_fpu_begin()/_end(). Note: all\nkernel tasks exposed in /proc have a valid task->fpu.\n\nSolution\n--------\nOne option is to silence the warning and check for NULL from\nx86_task_fpu(). However, that warning is fairly fresh and seems like a\ndefense against misuse of the FPU state in kernel threads.\n\nInstead, stop outputting AVX-512_elapsed_ms for kernel threads\naltogether. The data was garbage anyway because avx512_timestamp is\nonly updated for user threads, not kernel threads.\n\nIf anyone ever wants to track kernel thread AVX-512 use, they can come\nback later and do it properly, separate from this bug fix.\n\n[ dhansen: mostly rewrite changelog ]","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/2ca887e81095b99d890a8878841f36f4920181e6","https://git.kernel.org/stable/c/31cd31c9e17ece125aad27259501a2af69ccb020"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2025-38689","score":0.0014,"percentile":0.03315,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}