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CVE-2026-89634

9.1 · CRITICAL

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix ALIGN() overflow in symlink_data() error context loop The check added by commit 7d9a7f1f96cd ("smb/client: fix…

Published Sep 11, 2026EPSS 0.69%

Overview

CVE-2026-89634 is a critical-severity vulnerability. It was published on September 11, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.1, 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:

smb: client: fix ALIGN() overflow in symlink_data() error context loop

The check added by commit 7d9a7f1f96cd ("smb/client: fix possible

infinite loop and oob read in symlink_data()") compared the post-ALIGN

length against the remaining buffer, but ALIGN() itself can overflow:

for ErrorDataLength near UINT32_MAX (e.g. 0xFFFFFFF9), ALIGN(x, 8)

wraps to 0, so the subsequent bounds check passes, and the loop

advances by zero bytes leaving 'p' pointing into stale data.

Fix by checking the raw ErrorDataLength against the remaining space

before applying ALIGN(), then checking again after. Since raw_len is

bounded by the buffer, raw_len + 7 cannot overflow, so the second check

is an exact post-alignment bounds guard.

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/1f824f61d1df52392eaf0b74dfa5659d724fde30Refgit.kernel.org/stable/c/2b4a25baa0b936fef6915c0459925077b324ecafRefgit.kernel.org/stable/c/62656b024efc21c3230eade1a847f25871c3d2bbRefgit.kernel.org/stable/c/62a3025983c8c735a3c6fc85a59316f31b59af07Refgit.kernel.org/stable/c/657372ba6ea50b4474d2a6a610097eae8cd1f3e9Refgit.kernel.org/stable/c/b89d678f9eafcf8d74885983166ba26b40a04ea0

How CyberStrike helps

Frequently asked questions

What is CVE-2026-89634?

CVE-2026-89634 is a critical-severity vulnerability. It was published on September 11, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-89634?

This vulnerability has a CVSS 3.1 base score of 9.1, 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-2026-89634?

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-2026-89634?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-89634 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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