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CVE-2026-43364

5.5 · MEDIUM

In the Linux kernel, the following vulnerability has been resolved: ublk: fix NULL pointer dereference in ublk_ctrl_set_size() ublk_ctrl_set_size() unconditionally dereferences ub->ub_disk via se…

Published May 8, 2026CWE-476EPSS 0.16%

Overview

CVE-2026-43364 is a medium-severity vulnerability. It was published on May 8, 2026 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. 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:

ublk: fix NULL pointer dereference in ublk_ctrl_set_size()

ublk_ctrl_set_size() unconditionally dereferences ub->ub_disk via

set_capacity_and_notify() without checking if it is NULL.

ub->ub_disk is NULL before UBLK_CMD_START_DEV completes (it is only

assigned in ublk_ctrl_start_dev()) and after UBLK_CMD_STOP_DEV runs

(ublk_detach_disk() sets it to NULL). Since the UBLK_CMD_UPDATE_SIZE

handler performs no state validation, a user can trigger a NULL pointer

dereference by sending UPDATE_SIZE to a device that has been added but

not yet started, or one that has been stopped.

Fix this by checking ub->ub_disk under ub->mutex before dereferencing

it, and returning -ENODEV if the disk is not available.

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/25966fc097691e5c925ad080f64a2f19c5fd940aRefgit.kernel.org/stable/c/c28d945bfa92e15147e93b73f95345b9bec979b0Refgit.kernel.org/stable/c/f13fe6794726755a43090cb680c4c58cea6aa5f1

How CyberStrike helps

Frequently asked questions

What is CVE-2026-43364?

CVE-2026-43364 is a medium-severity vulnerability. It was published on May 8, 2026 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-43364?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-43364?

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-2026-43364?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-43364 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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