CVE-2026-64091

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

State: Published
Severity: 9.8 Critical
Published: Jul 19, 2026
Updated: Aug 5, 2026
Reserved: Jul 19, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	9.8 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	16116dac23396e73c01eeee97b102e4833a4b205 to before e4236bf3ec8d6bb15d0d8d825dcf9933a7d6666bAffected 16116dac23396e73c01eeee97b102e4833a4b205 to before 724a8eb4155669797c96b70d70e354284ae3b5a8Affected 16116dac23396e73c01eeee97b102e4833a4b205 to before 211ea59988e1cba43cb0367ad65d379b56f9c3bdAffected 16116dac23396e73c01eeee97b102e4833a4b205 to before 65a1e67339aa8c95ac544b796946af388930ee23Affected 16116dac23396e73c01eeee97b102e4833a4b205 to before b4d4efd4e351593c81e9293d4b4408d244fa5ee7Affected 16116dac23396e73c01eeee97b102e4833a4b205 to before 4cc85aec8d3c9ab4dc716dc9f1ed36fca16b227fAffected 16116dac23396e73c01eeee97b102e4833a4b205 to before 9a9c859457bc440a55773e01ff18b1bb5bab6836Affected 16116dac23396e73c01eeee97b102e4833a4b205 to before 94d27005016be15ffc638b2ecbc4d58805ad7b48Affected 3134c5a32810c510f1f447c135cec346acbb71c3Affected e861e03a1b5b615ad1b57b1802b17e260eedccfeAffected 0b81edc8818903c64c4d121bc51cd5825be8cc67Affected 90ae6475b1753f0c1a4c66034b5666de3189fac8Affected 3.16.60 to before 3.17Affected 4.4.217 to before 4.5Affected 4.9.217 to before 4.10Affected 4.14.174 to before 4.15Affected
LinuxLinux	4.17Affected before 4.17Not affected 5.10.259 through 5.10.Not affected 5.15.210 through 5.15.Not affected 6.1.176 through 6.1.Not affected 6.6.143 through 6.6.Not affected 6.12.93 through 6.12.Not affected 6.18.34 through 6.18.Not affected 7.0.11 through 7.0.*Not affected 7.1 and laterNot affected

Product

Versions

LinuxLinux

16116dac23396e73c01eeee97b102e4833a4b205 to before e4236bf3ec8d6bb15d0d8d825dcf9933a7d6666bAffected
16116dac23396e73c01eeee97b102e4833a4b205 to before 724a8eb4155669797c96b70d70e354284ae3b5a8Affected
16116dac23396e73c01eeee97b102e4833a4b205 to before 211ea59988e1cba43cb0367ad65d379b56f9c3bdAffected
16116dac23396e73c01eeee97b102e4833a4b205 to before 65a1e67339aa8c95ac544b796946af388930ee23Affected
16116dac23396e73c01eeee97b102e4833a4b205 to before b4d4efd4e351593c81e9293d4b4408d244fa5ee7Affected
16116dac23396e73c01eeee97b102e4833a4b205 to before 4cc85aec8d3c9ab4dc716dc9f1ed36fca16b227fAffected
16116dac23396e73c01eeee97b102e4833a4b205 to before 9a9c859457bc440a55773e01ff18b1bb5bab6836Affected
16116dac23396e73c01eeee97b102e4833a4b205 to before 94d27005016be15ffc638b2ecbc4d58805ad7b48Affected
3134c5a32810c510f1f447c135cec346acbb71c3Affected
e861e03a1b5b615ad1b57b1802b17e260eedccfeAffected
0b81edc8818903c64c4d121bc51cd5825be8cc67Affected
90ae6475b1753f0c1a4c66034b5666de3189fac8Affected
3.16.60 to before 3.17Affected
4.4.217 to before 4.5Affected
4.9.217 to before 4.10Affected
4.14.174 to before 4.15Affected

LinuxLinux

4.17Affected
before 4.17Not affected
5.10.259 through 5.10.*Not affected
5.15.210 through 5.15.*Not affected
6.1.176 through 6.1.*Not affected
6.6.143 through 6.6.*Not affected
6.12.93 through 6.12.*Not affected
6.18.34 through 6.18.*Not affected
7.0.11 through 7.0.*Not affected
7.1 and laterNot affected

References

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