{"cve":"CVE-2025-37949","nvd":{"published":"2025-05-20T16:15:32.920","modified":"2026-10-15T22:18:22.450","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nxenbus: Use kref to track req lifetime\n\nMarek reported seeing a NULL pointer fault in the xenbus_thread\ncallstack:\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nRIP: e030:__wake_up_common+0x4c/0x180\nCall Trace:\n <TASK>\n __wake_up_common_lock+0x82/0xd0\n process_msg+0x18e/0x2f0\n xenbus_thread+0x165/0x1c0\n\nprocess_msg+0x18e is req->cb(req).  req->cb is set to xs_wake_up(), a\nthin wrapper around wake_up(), or xenbus_dev_queue_reply().  It seems\nlike it was xs_wake_up() in this case.\n\nIt seems like req may have woken up the xs_wait_for_reply(), which\nkfree()ed the req.  When xenbus_thread resumes, it faults on the zero-ed\ndata.\n\nLinux Device Drivers 2nd edition states:\n\"Normally, a wake_up call can cause an immediate reschedule to happen,\nmeaning that other processes might run before wake_up returns.\"\n... which would match the behaviour observed.\n\nChange to keeping two krefs on each request.  One for the caller, and\none for xenbus_thread.  Each will kref_put() when finished, and the last\nwill free it.\n\nThis use of kref matches the description in\nDocumentation/core-api/kref.rst","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/0e94a246bb6d9538010b6c02d2b1d4717a97b2e5","https://git.kernel.org/stable/c/1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27","https://git.kernel.org/stable/c/2466b0f66795c3c426cacc8998499f38031dbb59","https://git.kernel.org/stable/c/4d260a5558df4650eb87bc41b2c9ac2d6b2ba447","https://git.kernel.org/stable/c/8b02f85e84dc6f7c150cef40ddb69af5a25659e5"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:01:57.636215869+00:00"},"epss":{"cve":"CVE-2025-37949","score":0.0024,"percentile":0.15004,"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."]}