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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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
Which versions are affected by CVE-2025-30211?
How do I fix CVE-2025-30211?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-30211 being exploited?
There is no known exploitation of CVE-2025-30211 in the wild and no public exploit code.
Sources
Also known as AZL-59350, AZL-59358, DEBIAN-CVE-2025-30211, GHSA-vvr3-fjhh-cfwc, OESA-2025-1363, OESA-2025-1364 and 5 more.