CVE Catalog

CVE-2026-64417

Low risk· EPSS 7%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.17%

7th percentile - higher than 7% of all known CVEs

Summary

In the Linux kernel, the shrinker debugfs mechanism has a NULL pointer dereference bug. The shrinker_debugfs_add() function creates "count" and "scan" debugfs files for every shrinker, assuming each implements both count_objects() and scan_objects(). However, some shrinkers (e.g., xen-backend) only set count_objects(), leaving scan_objects() as NULL, causing a kernel panic when writing to the "scan" file.

Risk Assessment

An attacker with local access can trigger a kernel panic (denial of service) by writing to the debugfs "scan" file of a shrinker that does not implement scan_objects().

Recommendation

Apply the Linux kernel patch that creates "count" and "scan" debugfs files only when the shrinker implements the corresponding callbacks.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: mm: shrinker: fix NULL pointer dereference in debugfs shrinker_debugfs_add() creates both "count" and "scan" debugfs files unconditionally. That assumes every shrinker implements both count_objects() and scan_objects(), which is not guaranteed. For example, the xen-backend shrinker sets count_objects() but leaves scan_objects() NULL, so writing to its scan file calls through a NULL function pointer and panics the kernel: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. Call Trace: <TASK> shrinker_debugfs_scan_write+0x12e/0x270 full_proxy_write+0x5f/0x90 vfs_write+0xde/0x420 ? filp_flush+0x75/0x90 ? filp_close+0x1d/0x30 ? do_dup2+0xb8/0x120 ksys_write+0x68/0xf0 ? filp_flush+0x75/0x90 do_syscall_64+0xb3/0x5b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e The count path has the same issue in principle if a shrinker omits count_objects(). To fix it, only create "count" and "scan" debugfs files when the corresponding callbacks are present.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS