Linux Kernel up to 7.3-rc3 Bridge br_mst_set_state race condition

CVSS Meta Temp Score
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CTI Interest Score
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8.6$0-$5k0.30-

Summaryinfo

A vulnerability categorized as very critical has been discovered in Linux Kernel up to 7.3-rc3. This affects the function br_mst_set_state of the component Bridge. The manipulation results in race condition. This vulnerability is known as CVE-2026-98301. It is possible to launch the attack remotely. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.3-rc3. It has been classified as very critical. Affected is the function br_mst_set_state of the component Bridge. The manipulation with an unknown input leads to a race condition vulnerability. CWE is classifying the issue as CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-98301 since 09/25/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 10/06/2026).

Upgrading to version 6.1.189, 6.6.158, 6.12.112, 6.18.54, 7.2.8 or 7.3-rc4 eliminates this vulnerability. Applying the patch b9661fd2423fc25e91e0517ecc0b6156ad83e3a8/6b431b63219853eef4054e2f1cb073d2ca2059b4/abf734d150c61acfdfee102169d0e5d1c482e285/d5c4ee1fa4e83a12afc051c831936cd8e006cde3/c40ed3e884c8dc0350f26484030438ef24208ff1/18a6fe05fb6e18de29fa90d388bb34044114b3d8 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.0
VulDB Meta Temp Score: 8.6

VulDB Base Score: 9.0
VulDB Temp Score: 8.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.189/6.6.158/6.12.112/6.18.54/7.2.8/7.3-rc4
Patch: b9661fd2423fc25e91e0517ecc0b6156ad83e3a8/6b431b63219853eef4054e2f1cb073d2ca2059b4/abf734d150c61acfdfee102169d0e5d1c482e285/d5c4ee1fa4e83a12afc051c831936cd8e006cde3/c40ed3e884c8dc0350f26484030438ef24208ff1/18a6fe05fb6e18de29fa90d388bb34044114b3d8

Timelineinfo

09/25/2026 CVE reserved
10/06/2026 +11 days Advisory disclosed
10/06/2026 +0 days VulDB entry created
10/06/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98301 (🔒)
GCVE (CVE): GCVE-0-2026-98301
GCVE (VulDB): GCVE-100-414240

Entryinfo

Created: 10/06/2026 13:57
Changes: 10/06/2026 13:57 (59)
Complete: 🔍
Cache ID: 216::103

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