CVE-2026-64089 Linux CVE debrief

Who should care

Users of the Linux kernel, particularly those who manage Linux-based systems, should be aware of this vulnerability. This includes Linux kernel maintainers, Linux distribution vendors, and end-users who rely on Linux-based systems. The vulnerability affects the batman-adv module, which is used in various Linux kernel deployments.

Technical summary

The Linux kernel has a vulnerability in the batman-adv module, specifically in the tt component. The vulnerability is caused by a type confusion issue with the last_changeset_len field, which is declared as a signed 16-bit integer (s16) but can hold values greater than 32767, causing it to wrap to a negative signed integer. This can lead to incorrect allocation and population of a buffer in the batadv_tt_prepare_tvlv_local_data function. The batman-adv module is used in various Linux kernel deployments, and users should review their systems for potential exposure.

Defensive priority

Medium

Recommended defensive actions

• Inventory and assess Linux kernel installations for potential exposure
• Apply patches or updates provided by the Linux kernel maintainers
• Monitor for any suspicious activity related to the batman-adv module
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-07-19T16:17:49.697Z and has not been modified since then. The NVD entry is currently Received. The source detail is limited, and defenders should verify the affected scope, severity, and vendor guidance. The batman-adv module is used in various Linux kernel deployments, and users should review their systems for potential exposure.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.