{"cve":"CVE-2026-64417","nvd":{"published":"2026-07-25T10:17:25.567","modified":"2026-09-04T15:24:56.173","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: shrinker: fix NULL pointer dereference in debugfs\n\nshrinker_debugfs_add() creates both \"count\" and \"scan\" debugfs files\nunconditionally.\n\nThat assumes every shrinker implements both count_objects() and\nscan_objects(), which is not guaranteed.  For example, the xen-backend\nshrinker sets count_objects() but leaves scan_objects() NULL, so writing\nto its scan file calls through a NULL function pointer and panics the\nkernel:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nRIP: 0010:0x0\nCode: Unable to access opcode bytes at 0xffffffffffffffd6.\nCall Trace:\n <TASK>\n shrinker_debugfs_scan_write+0x12e/0x270\n full_proxy_write+0x5f/0x90\n vfs_write+0xde/0x420\n ? filp_flush+0x75/0x90\n ? filp_close+0x1d/0x30\n ? do_dup2+0xb8/0x120\n ksys_write+0x68/0xf0\n ? filp_flush+0x75/0x90\n do_syscall_64+0xb3/0x5b0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThe count path has the same issue in principle if a shrinker omits\ncount_objects().\n\nTo fix it, only create \"count\" and \"scan\" debugfs files when the\ncorresponding callbacks are present.","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/006467ab932698612398f853344a7405164541f4","https://git.kernel.org/stable/c/09d2407985b8ce3e831f9d4310fe7ac06a6b3ae9","https://git.kernel.org/stable/c/36f8534f461222291a74156ab91f3ba9f09b6f93","https://git.kernel.org/stable/c/b9beed2322f3538b0d2d53307062da4102b8d8d8","https://git.kernel.org/stable/c/e30453c61e185e914fde83c650e268067b140218"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:46:40.600842820+00:00"},"epss":{"cve":"CVE-2026-64417","score":0.00123,"percentile":0.01992,"date":"2026-10-31"},"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."]}