{"id":"CVE-2025-37949","title":"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: 000000…","summary":"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: 000000…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-476"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 4.11, < 5.4.294","linux_kernel >= 5.5, < 5.10.238","linux_kernel >= 5.11, < 5.15.183","linux_kernel >= 5.16, < 6.1.139","linux_kernel >= 6.2, < 6.6.91","linux_kernel >= 6.7, < 6.12.29","linux_kernel >= 6.13, < 6.14.7","linux_kernel = 6.15","debian_linux = 11.0"],"patched":["linux_kernel 6.14.7"],"published":"2025-05-20","updated":"2026-10-15","sourceUpdated":"2026-10-15T22:18:22.450","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-37949","references":[{"url":"https://git.kernel.org/stable/c/0e94a246bb6d9538010b6c02d2b1d4717a97b2e5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2466b0f66795c3c426cacc8998499f38031dbb59","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/4d260a5558df4650eb87bc41b2c9ac2d6b2ba447","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8b02f85e84dc6f7c150cef40ddb69af5a25659e5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8e9c8a0393b5f85f1820c565ab8105660f4e8f92","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cbfaf46b88a4c01b64c4186cdccd766c19ae644c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f1bcac367bc95631afbb918348f30dec887d0e1b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd","cve.org"],"epss":0.0024,"epssPercentile":0.15072,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-15T21:46:21.911402Z"},"ingestedAt":"2026-10-15T22:48:25.486Z","slug":"CVE-2025-37949","body":"## Overview\n\nIn 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\n\n## Affected\n\n- `linux_kernel >= 4.11, < 5.4.294`\n- `linux_kernel >= 5.5, < 5.10.238`\n- `linux_kernel >= 5.11, < 5.15.183`\n- `linux_kernel >= 5.16, < 6.1.139`\n- `linux_kernel >= 6.2, < 6.6.91`\n- `linux_kernel >= 6.7, < 6.12.29`\n- `linux_kernel >= 6.13, < 6.14.7`\n- `linux_kernel = 6.15`\n- `debian_linux = 11.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.14.7`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}