# CVE-2025-30211: KEX init error results with excessive memory usage

> A maliciously formed KEX init message in Erlang/OTP can cause excessive memory allocation, leading to 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:** 28 Mar 2025
- **Updated:** 3 Nov 2025
- **Also known as:** AZL-59350, AZL-59358, DEBIAN-CVE-2025-30211, GHSA-vvr3-fjhh-cfwc, OESA-2025-1363, OESA-2025-1364, OESA-2025-1490, OESA-2025-1491, OESA-2025-1492, UBUNTU-CVE-2025-30211, USN-7425-1

## What is CVE-2025-30211?

CVE-2025-30211 is a high-severity denial of service vulnerability in erlang otp, published on 28 Mar 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Erlang/OTP is a set of libraries for the Erlang programming language. Prior to versions OTP-27.3.1, 26.2.5.10, and 25.3.2.19, a maliciously formed KEX init message can result with high memory usage. Implementation does not verify RFC specified limits on algorithm names (64 characters) provided in KEX init message. Big KEX init packet may lead to inefficient processing of the error data. As a result, large amount of memory will be allocated for processing malicious data. Versions OTP-27.3.1, OTP-26.2.5.10, and OTP-25.3.2.19 fix the issue. Some workarounds are available. One may set option `parallel_login` to `false` and/or reduce the `max_sessions` option.

Weakness: CWE-789 (Memory Allocation with Excessive Size Value)

## Which versions are affected by CVE-2025-30211?


## How do I fix CVE-2025-30211?

Upgrade to a fixed version.

## Is CVE-2025-30211 being exploited?

There is no known exploitation of CVE-2025-30211 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-30211 and fix it if it is affected.

What it is: CVE-2025-30211 is a high-severity denial of service vulnerability in erlang otp, published on 28 Mar 2025. 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-2025-30211 in the wild and no public exploit code.

Affected product: erlang otp. 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-2025-30211/ (Markdown: https://insights.sbomify.com/CVE-2025-30211/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-30211
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-30211
- OSV: https://osv.dev/vulnerability/CVE-2025-30211

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-30211/
Summaries are generated and may contain mistakes; the official description above is the record.