CVE-2026-64091

/// Technical description

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

batman-adv: tt: fix TOCTOU race for reported vlans

The local TT based TVLV is generated by first checking the number of VLANs

which have at least one TT entry. A new buffer with the correct size for

the VLANs is then allocated. Only then, the list of VLANs s used to fill

the VLAN entries in the buffer. During this time, the meshif_vlan_list_lock

is held. But the actual number of TT entries of each VLAN can still

increase during this time - just not the number of VLANs in the list.

But the prefilter used in the buffer size calculation might still cause an

increase of the number of VLANs which need to be stored. Simply because a

VLAN might now suddenly have at least one entry when it had none in the

pre-alloc check - and then needs to occupy space which was not allocated.

It is better to overestimate the buffer size at the beginning and then fill

the buffer only with the VLANs which are not empty.

/// 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