VulnerabilityPublished 28 Oct 2026

CVE-2026-99117: Linux kernel · net: bridge: mcast: don't truncate the port group walk on teardown

Source GCVE Database

Authoritative record:CVE-2026-99117

Not known to be exploited · fixed in b45e8c24608c992d1e2cea047eb5bcbfa537f86b : patch Linux kernel soon.

Data as of 28 Oct 2026, 14:14 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Patch: Available – fixed in b45e8c24608c992d1e2cea047eb5bcbfa537f86b, 8243d587a081e790ad96e80d48eef44d9f7ef005, 5a3f7a683aee56e1f15c9d53041f3236767eaae7

Exploitation evidence

Disclosed: evidence found.
CVE published 28 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-phhg-87vx-7j2v

What to do

Upgrade Linux kernel to b45e8c24608c992d1e2cea047eb5bcbfa537f86b, 8243d587a081e790ad96e80d48eef44d9f7ef005 or 5a3f7a683aee56e1f15c9d53041f3236767eaae7.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2, < b45e8c24608c992d1e2cea047eb5bcbfa537f86b	Fixed in b45e8c24608c992d1e2cea047eb5bcbfa537f86b
LinuxLinux	Affected ≥ b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2, < 8243d587a081e790ad96e80d48eef44d9f7ef005	Fixed in 8243d587a081e790ad96e80d48eef44d9f7ef005
LinuxLinux	Affected ≥ b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2, < 5a3f7a683aee56e1f15c9d53041f3236767eaae7	Fixed in 5a3f7a683aee56e1f15c9d53041f3236767eaae7
LinuxLinux	Affected =5.10	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel that changes the list unlinking method to preserve iteration pointers and adds checks to skip deleted groups during traversal. Users should apply the official Linux kernel updates that include this patch to remediate the issue. No additional mitigation steps are indicated.

Description

A use-after-free vulnerability in the Linux kernel's bridge multicast code was resolved by correcting how port groups are walked and deleted during teardown. The flaw involved improper handling of linked list pointers during multicast port group deletion, which could lead to a kernel slab-use-after-free bug detected by KASAN.

Impact

This vulnerability can cause a kernel use-after-free condition, leading to potential kernel crashes or memory corruption. The KASAN detection indicates a serious memory safety issue in the bridge multicast teardown code, which could affect system stability or security if exploited. No known exploits in the wild have been reported.

Summary

The vulnerability in the Linux kernel's bridge multicast subsystem arises from the use of hlist_for_each_entry_safe() to walk port->mglist in __br_multicast_disable_port_ctx() and br_multicast_del_port(). Concurrent deletions of entries by br_multicast_find_del_pg() via br_multicast_fwd_src_remove() or __fwd_del_star_excl() could clear the iterator's saved next pointer, prematurely terminating the walk. This leads to dangling pointers after port groups are freed, causing a KASAN slab-use-after-free error. The fix uses hlist_del_init_rcu() to unlink groups while preserving the next pointer, and adds logic to skip groups already deleted to avoid warnings during iteration. The fix ensures safe traversal and deletion under br->multicast_lock and proper synchronization with the garbage collection worker.

References

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