# CVE-2025-24934: SO_REUSEPORT_LB breaks connect(2) for UDP sockets

> Attackers can spoof UDP packets to connected sockets using SO_REUSEPORT_LB, bypassing connection state checks in the FreeBSD kernel.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 22 Oct 2025
- **Updated:** 23 Apr 2026
- **Also known as:** GHSA-h546-6x4h-w6q7

## What is CVE-2025-24934?

CVE-2025-24934 is a medium-severity vulnerability in FreeBSD, published on 22 Oct 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Software which sets SO_REUSEPORT_LB on a socket and then connects it to a host will not directly observe any problems.  However, due to its membership in a load-balancing group, that socket will receive packets originating from any host.  This breaks the contract of the connect(2) and implied connect via sendto(2), and may leave the application vulnerable to spoofing attacks.

The kernel failed to check the connection state of sockets when adding them to load-balancing groups.  Furthermore, when looking up the destination socket for an incoming packet, the kernel will match a socket belonging to a load-balancing group even if it is connected, in violation of the contract that connected sockets are only supposed to receive packets originating from the connected host.

Weakness: CWE-488 (Exposure of Data Element to Wrong Session)

## Which versions are affected by CVE-2025-24934?


## How do I fix CVE-2025-24934?

No fix has been published for CVE-2025-24934 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-24934 being exploited?

There is no known exploitation of CVE-2025-24934 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-24934 and fix it if it is affected.

What it is: CVE-2025-24934 is a medium-severity vulnerability in FreeBSD, published on 22 Oct 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2025-24934 in the wild and no public exploit code.

Affected product: FreeBSD. 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-2025-24934/ (Markdown: https://insights.sbomify.com/CVE-2025-24934/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-24934
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-24934
- OSV: https://osv.dev/vulnerability/CVE-2025-24934

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-24934/
Summaries are generated and may contain mistakes; the official description above is the record.