CVE-2026-52931 — Linux kernel batman-adv tp_meter uninitialized sender state flaw
In the Linux kernel, the following vulnerability has been resolved: batman-adv: tp_meter: avoid use of uninit sender vars batadv_tp_recv_ack() and batadv_tp_stop() are only valid for tp_vars in the BATADV_TP_SENDER role. When called with a BATADV_TP_RECEIVER role, it proceeds to read sender-only members that were never initialized, leading to undefined behavior. This can be triggered when a node that is currently acting as a receiver in an ongoing tp_meter session receives a malicious ACK packet. Guard against this by checking tp_vars->role immediately after the lookup and bailing out if it is not BATADV_TP_SENDER, before any of those members are accessed.
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
- EPSS 0.4% (30-day exploitation probability)+5
- 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, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Linux | Linux |
version 4.8≥ 33a3bb4a3345bb511f9c69c913da95d4693e2a4e and < 6c65cf23d4c6170fcf5714c32aa64689718cb142≥ 33a3bb4a3345bb511f9c69c913da95d4693e2a4e and < 85397e48afe6be83ffca5ad3f4792296bfc81d3d≥ 33a3bb4a3345bb511f9c69c913da95d4693e2a4e and < dc2ae5fbd2dadc26735092f140b246841d969a11≥ 33a3bb4a3345bb511f9c69c913da95d4693e2a4e and < ecdaa3e4d91040206afe21bc8a0d1198a0971ff3≥ 33a3bb4a3345bb511f9c69c913da95d4693e2a4e and < 53f931e0146ae5bdab4cba302646827d06b3794b≥ 33a3bb4a3345bb511f9c69c913da95d4693e2a4e and < 9884c9c02d3c90e9215db3c5128f59045d20ae91≥ 33a3bb4a3345bb511f9c69c913da95d4693e2a4e and < 1a21c055f66e78973712a4a1be2a554f1ee2e4f4 and 1 more≥ 33a3bb4a3345bb511f9c69c913da95d4693e2a4e and < 0e388af04b3958b178a1b979527f93eb46ea1fee |
Vulnerable | CVE Program (cve.org) e CISA ADP |
| Linux | Linux Kernel |
version 7.1-rc4≥ 4.8 and < 5.10.258version 7.1-rc3version 7.1-rc2version 7.1-rc1≥ 6.19 and < 7.0.11≥ 6.13 and < 6.18.34≥ 6.7 and < 6.12.92 and 3 more≥ 6.2 and < 6.6.142≥ 5.16 and < 6.1.175≥ 5.11 and < 5.15.209 |
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) EPSS over time FIRST
Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.76%
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).
Analysis and videos
CVE-2026-52931: Linux kernel batman-adv tp_meter uninitialized sender state flaw
CVE-2026-52931 is a critical flaw in the batman-adv tp_meter component of the Linux kernel, where ACK handling and session stop routines can read sender-only data while a node is acting as receiver. The record assigns CVSS 3.1 base score 9.8 with a network attack vector and no privileges or user interaction required. The upstream fix adds a role check that rejects non-sender states before that data is accessed, and no confirmed exploitation appears in the sources consulted.
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 13, 2026 – Oct 13, 2026
References
8 on the record
- git.kernel.org/stable/c/0e388af04b3958b178a1b979527f93eb46ea1fee
- git.kernel.org/stable/c/1a21c055f66e78973712a4a1be2a554f1ee2e4f4
- git.kernel.org/stable/c/53f931e0146ae5bdab4cba302646827d06b3794b
- git.kernel.org/stable/c/9884c9c02d3c90e9215db3c5128f59045d20ae91
- git.kernel.org/stable/c/dc2ae5fbd2dadc26735092f140b246841d969a11
- git.kernel.org/stable/c/6c65cf23d4c6170fcf5714c32aa64689718cb142
- git.kernel.org/stable/c/85397e48afe6be83ffca5ad3f4792296bfc81d3d
- git.kernel.org/stable/c/ecdaa3e4d91040206afe21bc8a0d1198a0971ff3
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 15h
- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 15h
- 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
- Unknown CVE-2026-98428 ALSA: usb: 6fire: Avoid embedded URBs 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 CISA SSVC assessment.
- No CWE classification.
- 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-2026-52931 is "Linux kernel batman-adv tp_meter uninitialized sender state flaw", 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. EPSS 0.40% estimates the probability of exploitation in 30 days; neither replaces your asset context. 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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