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CVE-2026-64089

9.8 · CRITICAL

In the Linux kernel, the following vulnerability has been resolved: batman-adv: tt: fix negative last_changeset_len batadv_piv_tt::last_changeset_len len was declared as s16, but the field is nev…

Published Jul 19, 2026EPSS 0.55%

Overview

CVE-2026-64089 is a critical-severity vulnerability. It was published on July 19, 2026 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:

batman-adv: tt: fix negative last_changeset_len

batadv_piv_tt::last_changeset_len len was declared as s16, but the field is

never intended to hold a negative value. When a value greater than 32767 is

assigned, it wraps to a negative signed integer.

In batadv_send_my_tt_response(), last_changeset_len is temporarily widened

to s32. The incorrectly negative s16 value propagates into the s32, causing

batadv_tt_prepare_tvlv_local_data() to allocate a full sized buffer but

populates only a small portion of it with the collected changeset. All

remaining bits are kept uninitialized.

Using an u16 avoids this type confusion and ensures that no (negative) sign

extension is performed in batadv_send_my_tt_response().

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/179eb62506a02d00370bd6478898cb632e10986cRefgit.kernel.org/stable/c/22d59c72f4a47ffec121d0610f70d0d70c3c11c8Refgit.kernel.org/stable/c/55dc41fe8821e9a849e147255ad572bc933a9d15Refgit.kernel.org/stable/c/6314089acf0ddf64376fdc0b1420695504c73f52Refgit.kernel.org/stable/c/c424e8519ac78eac5d9f4eecf06208a0d619ec14Refgit.kernel.org/stable/c/d29abf70c665730e249d2ec8e1402095ae26bceeRefgit.kernel.org/stable/c/eb235472b52ef36981c5aad330485eaf2382c53bRefgit.kernel.org/stable/c/fc92cdfcb295cefa4344d71a527d61b638b7bfc4

How CyberStrike helps

Frequently asked questions

What is CVE-2026-64089?

CVE-2026-64089 is a critical-severity vulnerability. It was published on July 19, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-64089?

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-2026-64089?

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-2026-64089?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-64089 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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