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CVE-2025-21954

9.8 · CRITICAL

In the Linux kernel, the following vulnerability has been resolved: netmem: prevent TX of unreadable skbs Currently on stable trees we have support for netmem/devmem RX but not TX.

Published Apr 1, 2025CWE-401EPSS 0.50%

Overview

CVE-2025-21954 is a critical-severity vulnerability. It was published on April 1, 2025 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

netmem: prevent TX of unreadable skbs

Currently on stable trees we have support for netmem/devmem RX but not

TX. It is not safe to forward/redirect an RX unreadable netmem packet

into the device's TX path, as the device may call dma-mapping APIs on

dma addrs that should not be passed to it.

Fix this by preventing the xmit of unreadable skbs.

Tested by configuring tc redirect:

sudo tc qdisc add dev eth1 ingress

sudo tc filter add dev eth1 ingress protocol ip prio 1 flower ip_proto \

tcp src_ip 192.168.1.12 action mirred egress redirect dev eth1

Before, I see unreadable skbs in the driver's TX path passed to dma

mapping APIs.

After, I don't see unreadable skbs in the driver's TX path passed to dma

mapping APIs.

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/1c17c8ced25c5fbe424c7ad7ea11d33014a986b1Refgit.kernel.org/stable/c/454825019d2f0c59e5174ece9e713f45ad80beffRefgit.kernel.org/stable/c/f3600c867c99a2cc8038680ecf211089c50e7971

How CyberStrike helps

Frequently asked questions

What is CVE-2025-21954?

CVE-2025-21954 is a critical-severity vulnerability. It was published on April 1, 2025 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2025-21954?

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2025-21954?

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-2025-21954?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-21954 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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