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Actively exploited

CVE-2025-32433 Erlang Erlang/OTP SSH Server Missing Authentication for Critical Function Vulnerability

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.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch nowCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 9 Jun 2025.
  • Rated Critical severity (CVSS 10.0, scored by Vendor).
  • This product type is often exposed to the internet, which is where attackers scan for it first.
  • Named in Cybergen threat actor reporting: The Gentlemen.
  • It has been in the catalogue for 515 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

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.

Affected Versions

ProductVersions
erlang otp>= OTP-27.0-rc1, < OTP-27.3.3
>= OTP-26.0-rc1, < OTP-26.2.5.11
< OTP-25.3.2.20

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Erlang/OTP. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated critical, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 30 Jun 2025 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2025-32433
  3. CVE record: CVE-2025-32433
  4. FIRST EPSS
  5. sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-erlang-otp-ssh-xyZZy
  6. github.com/erlang/otp/security/advisories/GHSA-37cp-fgq5-7wc2
  7. github.com/erlang/otp/commit/0fcd9c56524b28615e8ece65fc0c3f66ef6e4c12
  8. github.com/erlang/otp/commit/6eef04130afc8b0ccb63c9a0d8650209cf54892f
  9. github.com/erlang/otp/commit/b1924d37fd83c070055beb115d5d6a6a9490b891