CVE Catalog

CVE-2025-39941

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.09%

1th percentile - higher than 1% of all known CVEs

Summary

A race condition during concurrent writes to the same zram index in the Linux kernel's zram driver was found. It leads to leaked zsmalloc handles because zs_free() is called too early.

Risk Assessment

Leaked zsmalloc handles could lead to memory exhaustion and system crashes.

Recommendation

Apply the Linux kernel patch that resets the zram entry right before setting a new handle, under the same slot lock.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: zram: fix slot write race condition Parallel concurrent writes to the same zram index result in leaked zsmalloc handles. Schematically we can have something like this: CPU0 CPU1 zram_slot_lock() zs_free(handle) zram_slot_lock() zram_slot_lock() zs_free(handle) zram_slot_lock() compress compress handle = zs_malloc() handle = zs_malloc() zram_slot_lock zram_set_handle(handle) zram_slot_lock zram_slot_lock zram_set_handle(handle) zram_slot_lock Either CPU0 or CPU1 zsmalloc handle will leak because zs_free() is done too early. In fact, we need to reset zram entry right before we set its new handle, all under the same slot lock scope.

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