# CVE-2025-40833: Null dereference in IE/PB LINK HA

> Attackers can cause denial of service on Siemens industrial network devices via crafted IPv4 requests, requiring manual restart for recovery.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 May 2026
- **Updated:** 11 Aug 2026
- **Also known as:** GHSA-9483-pcvr-wj53

## What is CVE-2025-40833?

CVE-2025-40833 is a high-severity vulnerability in Siemens IE/PB LINK HA, published on 12 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The affected devices contain a null pointer dereference vulnerability while processing specially crafted IPv4 requests. This could allow an attacker to cause denial of service condition. A manual restart is required to recover the system.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-40833?


## How do I fix CVE-2025-40833?

No fix has been published for CVE-2025-40833 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-40833 being exploited?

There is no known exploitation of CVE-2025-40833 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40833 and fix it if it is affected.

What it is: CVE-2025-40833 is a high-severity vulnerability in Siemens IE/PB LINK HA, published on 12 May 2026. 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-2025-40833 in the wild and no public exploit code.

Affected product: Siemens IE/PB LINK HA. 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-2025-40833/ (Markdown: https://insights.sbomify.com/CVE-2025-40833/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40833
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40833
- OSV: https://osv.dev/vulnerability/CVE-2025-40833

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40833/
Summaries are generated and may contain mistakes; the official description above is the record.