CVE-2026-64091 — batman-adv: tt: fix TOCTOU race for reported vlans
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.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Technical severity (critical)+10
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (logic error), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Linux | Linux |
version e861e03a1b5b615ad1b57b1802b17e260eedccfe≥ 16116dac23396e73c01eeee97b102e4833a4b205 and < 724a8eb4155669797c96b70d70e354284ae3b5a8≥ 16116dac23396e73c01eeee97b102e4833a4b205 and < 211ea59988e1cba43cb0367ad65d379b56f9c3bd≥ 16116dac23396e73c01eeee97b102e4833a4b205 and < 65a1e67339aa8c95ac544b796946af388930ee23≥ 16116dac23396e73c01eeee97b102e4833a4b205 and < b4d4efd4e351593c81e9293d4b4408d244fa5ee7≥ 16116dac23396e73c01eeee97b102e4833a4b205 and < 4cc85aec8d3c9ab4dc716dc9f1ed36fca16b227f≥ 16116dac23396e73c01eeee97b102e4833a4b205 and < 9a9c859457bc440a55773e01ff18b1bb5bab6836≥ 16116dac23396e73c01eeee97b102e4833a4b205 and < 94d27005016be15ffc638b2ecbc4d58805ad7b48 and 9 moreversion 3134c5a32810c510f1f447c135cec346acbb71c3≥ 16116dac23396e73c01eeee97b102e4833a4b205 and < e4236bf3ec8d6bb15d0d8d825dcf9933a7d6666bversion 0b81edc8818903c64c4d121bc51cd5825be8cc67version 90ae6475b1753f0c1a4c66034b5666de3189fac8≥ 3.16.60 and < 3.17≥ 4.4.217 and < 4.5≥ 4.9.217 and < 4.10≥ 4.14.174 and < 4.15version 4.17 |
Vulnerable | CVE Program (cve.org) e CISA ADP |
| Linux | Linux Kernel |
≥ 6.13 and < 6.18.34≥ 4.4.217 and < 4.5≥ 4.9.217 and < 4.10≥ 4.14.174 and < 4.15≥ 4.17.1 and < 5.10.259≥ 5.11 and < 5.15.210≥ 5.16 and < 6.1.176≥ 6.2 and < 6.6.143 and 9 more≥ 6.7 and < 6.12.93≥ 3.16.60 and < 3.17≥ 6.19 and < 7.0.11version 4.17version 4.17-rc7version 7.1-rc1version 7.1-rc2version 7.1-rc3version 7.1-rc4 |
Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 9.8 | CVSS 3.1 | Critical | 3.9 | 5.9 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database |
| 9.8 | CVSS 3.1 | Critical | — | — | Linux via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · linux/linux
- Record published
- Fix documented
- CVSS changed · 9.8
- Source status changed · → Analyzed
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
8 on the record
- git.kernel.org/stable/c/724a8eb4155669797c96b70d70e354284ae3b5a8
- git.kernel.org/stable/c/94d27005016be15ffc638b2ecbc4d58805ad7b48
- git.kernel.org/stable/c/211ea59988e1cba43cb0367ad65d379b56f9c3bd
- git.kernel.org/stable/c/65a1e67339aa8c95ac544b796946af388930ee23
- git.kernel.org/stable/c/4cc85aec8d3c9ab4dc716dc9f1ed36fca16b227f
- git.kernel.org/stable/c/b4d4efd4e351593c81e9293d4b4408d244fa5ee7
- git.kernel.org/stable/c/9a9c859457bc440a55773e01ff18b1bb5bab6836
- git.kernel.org/stable/c/e4236bf3ec8d6bb15d0d8d825dcf9933a7d6666b
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 9h
- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 9h
- Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d
- Unknown CVE-2026-98431 RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency 1d
- Unknown CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 1d
- Unknown CVE-2026-98429 RDMA/efa: Keep EQ resources alive while IRQ is registered 1d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No FIRST EPSS score.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-64091 is "batman-adv: tt: fix TOCTOU race for reported vlans", rated Critical. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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