VulnerabilityPublished 28 Oct 2026

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

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in b45e8c24608c992d1e2cea047eb5bcbfa537f86b : update Linux kernel when convenient.

Data as of 28 Oct 2026, 10:58 UTC

Severity

Unrated

Rated by Threat Radar · 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.

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–

Description

In the Linux kernel, the following vulnerability has been resolved: net: bridge: mcast: don't truncate the port group walk on teardown __br_multicast_disable_port_ctx() and br_multicast_del_port() walk port->mglist with hlist_for_each_entry_safe(). However, br_multicast_find_del_pg() can also delete other entries from the same list through br_multicast_fwd_src_remove() or __fwd_del_star_excl(). If such an entry is the iterator's saved next node, hlist_del_init() clears its ->next and terminates the walk early. The reproducer triggers this in both teardown walks, leaving port groups in the bridge mdb with a dangling ->key.port after del_nbp() frees the port: BUG: KASAN: slab-use-after-free in __mdb_fill_info+0x1191/0x1320 __mdb_fill_info+0x1191/0x1320 br_mdb_dump+0x594/0xe40 rtnl_mdb_dump+0x1cf/0x5d0 Use hlist_del_init_rcu() to unlink the group while preserving ->next. br_multicast_del_pg() and the teardown walks run under br->multicast_lock. The GC worker must acquire the same lock before detaching the group for destruction, so the node remains alive while the walk uses the preserved pointer. Preserving ->next means a walk can now reach a group that an earlier iteration already deleted as a side effect. That group is off mp->ports, so br_multicast_find_del_pg() would fall through its port scan and hit the trailing WARN_ON(1). Skip such groups at the top of that helper: a port group is put on port->mglist when it is created and only unlinked when it is deleted, so hlist_unhashed() identifies exactly this case.

References

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