# CVE-2024-26826: mptcp: fix data re-injection from stale subflow

> A logic error in the Linux kernel MPTCP scheduler prevents data re-injection from stale subflows, potentially causing connection stalls or denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Apr 2024
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2024-26826, DEBIAN-CVE-2024-26826, GHSA-vfr6-9rmm-7rvg, UBUNTU-CVE-2024-26826

## What is CVE-2024-26826?

CVE-2024-26826 is a high-severity denial of service vulnerability in Linux kernel, published on 17 Apr 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

mptcp: fix data re-injection from stale subflow

When the MPTCP PM detects that a subflow is stale, all the packet
scheduler must re-inject all the mptcp-level unacked data. To avoid
acquiring unneeded locks, it first try to check if any unacked data
is present at all in the RTX queue, but such check is currently
broken, as it uses TCP-specific helper on an MPTCP socket.

Funnily enough fuzzers and static checkers are happy, as the accessed
memory still belongs to the mptcp_sock struct, and even from a
functional perspective the recovery completed successfully, as
the short-cut test always failed.

A recent unrelated TCP change - commit d5fed5addb2b ("tcp: reorganize
tcp_sock fast path variables") - exposed the issue, as the tcp field
reorganization makes the mptcp code always skip the re-inection.

Fix the issue dropping the bogus call: we are on a slow path, the early
optimization proved once again to be evil.

## Which versions are affected by CVE-2024-26826?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-26826?

Apply the vendor's patch.

## Is CVE-2024-26826 being exploited?

There is no known exploitation of CVE-2024-26826 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-26826 and fix it if it is affected.

What it is: CVE-2024-26826 is a high-severity denial of service vulnerability in Linux kernel, published on 17 Apr 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-26826 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-26826/ (Markdown: https://insights.sbomify.com/CVE-2024-26826/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26826
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26826
- OSV: https://osv.dev/vulnerability/CVE-2024-26826

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26826/
Summaries are generated and may contain mistakes; the official description above is the record.