# CVE-2018-25299: Prime95 29.4b8 Local Buffer Overflow via SEH

> Local attackers can execute arbitrary code via buffer overflow in Prime95's proxy settings, requiring specific configuration to exploit.

- **Severity:** High 8.6 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Apr 2026
- **Updated:** 30 Apr 2026
- **Also known as:** GHSA-vp92-854v-9rq4

## What is CVE-2018-25299?

CVE-2018-25299 is a high-severity memory corruption vulnerability in Mersenne Prime95, published on 29 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Prime95 29.4b8 contains a local buffer overflow vulnerability that allows attackers to execute arbitrary code by exploiting structured exception handling (SEH) mechanisms. Attackers can inject malicious payload through the optional proxy hostname field in the PrimeNet connection settings to trigger the overflow and execute system commands.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2018-25299?


## How do I fix CVE-2018-25299?

No fix has been published for CVE-2018-25299 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-25299 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2018-25299 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-25299 and fix it if it is affected.

What it is: CVE-2018-25299 is a high-severity memory corruption vulnerability in Mersenne Prime95, published on 29 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2018-25299 exists.

Affected product: Mersenne Prime95. 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-2018-25299/ (Markdown: https://insights.sbomify.com/CVE-2018-25299/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-25299
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-25299
- OSV: https://osv.dev/vulnerability/CVE-2018-25299

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-25299/
Summaries are generated and may contain mistakes; the official description above is the record.