Vulnerability in Linux

[ Description ]Official 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.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund5 Oct 2026WID-SEC-2026-3743

  Linux Kernel: Multiple vulnerabilities Translated from German

  Risk mediumCVE-2026-98221CVE-2026-98181CVE-2026-98248+204 more CVEs

[ References ]References

• git.kernel.org/stable/c/18a6fe05fb6e18de29fa90d388bb34044114b3d8
• git.kernel.org/stable/c/6b431b63219853eef4054e2f1cb073d2ca2059b4
• git.kernel.org/stable/c/abf734d150c61acfdfee102169d0e5d1c482e285
• git.kernel.org/stable/c/b9661fd2423fc25e91e0517ecc0b6156ad83e3a8
• git.kernel.org/stable/c/c40ed3e884c8dc0350f26484030438ef24208ff1
• git.kernel.org/stable/c/d5c4ee1fa4e83a12afc051c831936cd8e006cde3