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CVE-2025-39941

7.8 · HIGH

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.

Published Oct 4, 2025CWE-362EPSS 0.10%

Overview

CVE-2025-39941 is a high-severity vulnerability. It was published on October 4, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/ce4be9e4307c5a60701ff6e0cafa74caffdc54ceRefgit.kernel.org/stable/c/ff750e9f2c4d63854c33967d1646b5e89a9a19a2

How CyberStrike helps

Frequently asked questions

What is CVE-2025-39941?

CVE-2025-39941 is a high-severity vulnerability. It was published on October 4, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2025-39941?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-39941?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-39941?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-39941 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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