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CVE-2026-98301

Linux: net: bridge: mst: move switchdev call outside rcu

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.18%Chance of exploitation activity in the next 30 days, higher than 7% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in6b431b63219853eef4054e2f1cb073d2ca2059b4Also 18a6fe05fb6e18de29fa90d388bb34044114b3d8, 6.1.189 and 3 moreCVE List
Published6 Oct 2026Updated 19 Oct 2026CVE List

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

Text from CVE List

Affected versions 20

  • Linuxaffected: 8ca9a750fc711911ef616ceb627d07357b04545e before b9661fd2423fc25e91e0517ecc0b6156ad83e3a8CVE List
  • Linuxaffected: 4488617e5e995a09abe4d81add5fb165674edb59 before 6b431b63219853eef4054e2f1cb073d2ca2059b4CVE List
  • Linuxaffected: 3a7c1661ae1383364cd6092d851f5e5da64d476b before abf734d150c61acfdfee102169d0e5d1c482e285CVE List
  • Linuxaffected: 3a7c1661ae1383364cd6092d851f5e5da64d476b before d5c4ee1fa4e83a12afc051c831936cd8e006cde3CVE List
  • Linuxaffected: 3a7c1661ae1383364cd6092d851f5e5da64d476b before c40ed3e884c8dc0350f26484030438ef24208ff1CVE List
  • Linuxaffected: 3a7c1661ae1383364cd6092d851f5e5da64d476b before 18a6fe05fb6e18de29fa90d388bb34044114b3d8CVE List
  • Linuxaffected: a2b01e65d9ba8af2bb086d3b7288ca53a07249acCVE List
  • Linuxaffected: e43dd2b1ec746e105b7db5f9ad6ef14685a615a4CVE List
  • Linuxaffected: 6.1.93 before 6.1.189CVE List
  • Linuxaffected: 6.6.33 before 6.6.158CVE List
  • Linuxaffected: 6.8.12 before 6.9CVE List
  • Linuxaffected: 6.9.3 before 6.10CVE List
  • Linuxaffected: 6.10CVE List
  • Linuxunaffected: all versions before 6.10CVE List
  • Linuxunaffected: 6.1.189 through 6.1.*CVE List
  • Linuxunaffected: 6.6.158 through 6.6.*CVE List
  • Linuxunaffected: 6.12.112 through 6.12.*CVE List
  • Linuxunaffected: 6.18.54 through 6.18.*CVE List
  • Linuxunaffected: 7.2.8 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 6