VulnerabilityPublished 23 Oct 2026

CVE-2026-98881: Linux kernel · net: bridge: remove stale rcu_barrier() in br_multicast_dev_del()

Source GCVE Database

Authoritative record:CVE-2026-98881· Medium

Not known to be exploited · fixed in f0018acf0b66f93a292667c9a9c2a26c570cf270 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 12:55 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f0018acf0b66f93a292667c9a9c2a26c570cf270, ac0e823a228f94ad9d7a3d876cc07e59a7afb806, 39679927fa7aaf4601119f7234342d1b5d4f6f84 +4

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-52xp-vqwj-rp88

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 19e3a9c90c53479fecaa02307bf2db5ab8b3ffe3, < f0018acf0b66f93a292667c9a9c2a26c570cf270	Fixed in f0018acf0b66f93a292667c9a9c2a26c570cf270
LinuxLinux	Affected ≥ 19e3a9c90c53479fecaa02307bf2db5ab8b3ffe3, < ac0e823a228f94ad9d7a3d876cc07e59a7afb806	Fixed in ac0e823a228f94ad9d7a3d876cc07e59a7afb806
LinuxLinux	Affected ≥ 19e3a9c90c53479fecaa02307bf2db5ab8b3ffe3, < 39679927fa7aaf4601119f7234342d1b5d4f6f84	Fixed in 39679927fa7aaf4601119f7234342d1b5d4f6f84
LinuxLinux	Affected ≥ 19e3a9c90c53479fecaa02307bf2db5ab8b3ffe3, < 0443f6aac6bf6a91e406273fdda11497cef6ad07	Fixed in 0443f6aac6bf6a91e406273fdda11497cef6ad07
LinuxLinux	Affected ≥ 19e3a9c90c53479fecaa02307bf2db5ab8b3ffe3, < 372ee8fbe0f796031c60f676ec90f0788c26523d	Fixed in 372ee8fbe0f796031c60f676ec90f0788c26523d
LinuxLinux	Affected ≥ 19e3a9c90c53479fecaa02307bf2db5ab8b3ffe3, < 35f9f11740515a10b084adfb1ce691351f2452ab	Fixed in 35f9f11740515a10b084adfb1ce691351f2452ab

AI-suggested

A fix has been implemented in the Linux kernel by removing the stale rcu_barrier() call in br_multicast_dev_del(). Users should update to the kernel version that includes this fix. Since this is a kernel-level fix, applying the official kernel update from the vendor or distribution is the recommended remediation.

Description

A vulnerability in the Linux kernel's network bridge code was resolved by removing a stale rcu_barrier() call in the br_multicast_dev_del() function. The obsolete rcu_barrier() caused excessive RTNL (runtime network link) pressure and could lead to task blocking and performance issues. This fix addresses the problem by eliminating the unnecessary synchronization call that originated from older code patterns.

Impact

The vulnerability causes excessive RTNL pressure in the kernel, leading to tasks being blocked on mutexes and potential performance degradation or system responsiveness issues. There is no indication of direct security compromise such as privilege escalation or code execution from the provided data.

Summary

The Linux kernel vulnerability CVE-2026-98881 involves a stale rcu_barrier() call in the net/bridge/br_multicast.c file, specifically in the br_multicast_dev_del() function. This rcu_barrier() was a remnant from when call_rcu() was used, but since kfree_rcu() replaced it, the barrier became problematic. It caused extreme RTNL pressure and task blocking, as evidenced by syzbot reports showing tasks blocked on mutexes likely owned by kernel worker threads. The fix removes this obsolete rcu_barrier() to prevent these issues.

References

Community reviews

Loading reviews…