net: bridge: mcast: don't truncate the port group walk on teardown

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-99117
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-28 11:17:31 UTC
Updated2026-10-31 13:17:56 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001260000 probability, percentile 0.022720000 (date 2026-11-02)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2 be331b23c650de9518f8266b901d8abb9b36af77 git Not specified
CNA Linux Linux affected b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2 ab836d56ff43f2e7927e88c83cd02c47a98a672e git Not specified
CNA Linux Linux affected b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2 025c25ad73323c7dc5af4ee97fe0a2c0b3c177c8 git Not specified
CNA Linux Linux affected b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2 b0db9f4ff402becff710ab27dbd9f6fe4850b47e git Not specified
CNA Linux Linux affected b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2 e69d4927dacd6ddaff09777a89efc0d3143d3b0d git Not specified
CNA Linux Linux affected b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2 8243d587a081e790ad96e80d48eef44d9f7ef005 git Not specified
CNA Linux Linux affected b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2 b45e8c24608c992d1e2cea047eb5bcbfa537f86b git Not specified
CNA Linux Linux affected b08123684bd55fa6d6ee4b52d4ae3040fadb5aa2 5a3f7a683aee56e1f15c9d53041f3236767eaae7 git Not specified
CNA Linux Linux affected 5.10 Not specified
CNA Linux Linux unaffected 5.10 semver Not specified
CNA Linux Linux unaffected 5.10.273 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.224 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.191 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.161 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.115 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.59 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.13 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/025c25ad73323c7dc5af4ee97fe0a2c0b3c177c8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b0db9f4ff402becff710ab27dbd9f6fe4850b47e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e69d4927dacd6ddaff09777a89efc0d3143d3b0d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/be331b23c650de9518f8266b901d8abb9b36af77 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ab836d56ff43f2e7927e88c83cd02c47a98a672e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b45e8c24608c992d1e2cea047eb5bcbfa537f86b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8243d587a081e790ad96e80d48eef44d9f7ef005 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5a3f7a683aee56e1f15c9d53041f3236767eaae7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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