CVE-2025-32433
CVE-2025-32433 is a security flaw in Erlang/OTP. Attackers can run their own code on Erlang/OTP from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 9 Jun 2025.[1]
Erlang/OTP is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Erlang has published a fix or advice.
Description
CISA calls it an SSH server missing authentication for critical function in Erlang Erlang/OTP. In its words: “Erlang Erlang/OTP SSH server contains a missing authentication for critical function vulnerability. This could allow an attacker to execute arbitrary commands without valid credentials, potentially leading to unauthenticated remote code execution (RCE). By exploiting a flaw in how SSH protocol messages are handled, a malicious actor could gain unauthorized access to affected systems. This vulnerability could affect various products that implement Erlang/OTP SSH server, including—but not limited to—Cisco, NetApp, and SUSE.”[1]
The CVE record adds: “Erlang/OTP is a set of libraries for the Erlang programming language. Prior to versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20, a SSH server may allow an attacker to perform unauthenticated remote code execution (RCE). By exploiting a flaw in SSH protocol message handling, a malicious actor could gain unauthorized access to affected systems and execute arbitrary commands without valid credentials. This issue is patched in versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20. A temporary workaround involves disabling the SSH server or to prevent access via firewall rules.”[2]
The underlying weakness is missing authentication (CWE-306), in MITRE’s list of common software weaknesses.
It scores 10.0 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Erlang’s advisory has them[3]. CISA names the product as Erlang Erlang/OTP.
Most families won’t have Erlang/OTP; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 9 Jun 2025, 54 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 30 Jun 2025 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 99%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
Erlang has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.Erlang/OTP is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 30 Jun 2025 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 10.0.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 99%.[4] |
See also
Other missing authentication flaws
- CVE-2026-111357, Ivanti Connect Secure: missing authentication for critical function ·
- CVE-2026-67277, MikroTik RouterOS: missing authentication for critical function ·
- CVE-2026-81578, PaperCut NG/MF: missing authentication for critical function ·
- CVE-2026-72529, TrueConf Server: missing authentication for critical function ·
- CVE-2026-56164, Microsoft SharePoint Server: missing authentication for critical function ·
Added the same day
- CVE-2024-42009, Roundcube Webmail: cross-site scripting ·
References
- ^ Cybersecurity and Infrastructure Security Agency. “Erlang Erlang/OTP SSH Server Missing Authentication for Critical Function Vulnerability”. Known Exploited Vulnerabilities Catalog, added 9 Jun 2025.
- ^ National Institute of Standards and Technology. “CVE-2025-32433 Detail”. National Vulnerability Database, published 16 Apr 2025.
- ^ Erlang. Advisories and fixes: github.com, sec.cloudapps.cisco.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.989, percentile 99.9, 31 Oct 2026.
- CVE Program. “CVE-2025-32433”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.