Erlang Erlang/OTP SSH Server Missing Authentication for Critical Function
CVE-2025-32433 is a critical-severity missing authentication for critical functionality vulnerability in otp from Erlang, with a CVSS 3.1 base score of 10.0 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected otp versions: >= OTP-27.0-rc1, < OTP-27.3.3; >= OTP-26.0-rc1, < OTP-26.2.5.11; < OTP-25.3.2.20. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on June 9, 2025, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Erlang/otp to 25.3.2.20 or 26.2.5.11 or 27.3.3, whichever matches your release line, or a later version.
- Update Confd Basic to 7.7.19.1 or 8.1.16.2 or 8.2.11.1 or 8.3.8.1, whichever matches your release line, or a later version.
- Update Network Services Orchestrator to 5.7.19.1 or 6.1.16.2 or 6.2.11.1 or 6.3.8.1, whichever matches your release line, or a later version.
- 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.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Erlang | otp | >= OTP-27.0-rc1, < OTP-27.3.3; >= OTP-26.0-rc1, < OTP-26.2.5.11; < OTP-25.3.2.20 | Not stated |
| Erlang | Erlang/otp | before 25.3.2.20; 26.0 up to, but not including, 26.2.5.11; 27.0 up to, but not including, 27.3.3 | 25.3.2.20, 26.2.5.11, 27.3.3 |
| Cisco | Confd Basic | before 7.7.19.1; 8.0.18 up to, but not including, 8.1.16.2; 8.2 up to, but not including, 8.2.11.1; 8.3 up to, but not including, 8.3.8.1; 8.4 up to, but not including, 8.4.4.1 | 7.7.19.1, 8.1.16.2, 8.2.11.1, 8.3.8.1, 8.4.4.1 |
| Cisco | Network Services Orchestrator | before 5.7.19.1; 5.8 up to, but not including, 6.1.16.2; 6.2 up to, but not including, 6.2.11.1; 6.3 up to, but not including, 6.3.8.1; 6.4 up to, but not including, 6.4.1.1; 6.4.2 up to, but not including, 6.4.4.1 | 5.7.19.1, 6.1.16.2, 6.2.11.1, 6.3.8.1, 6.4.1.1, 6.4.4.1 |
| Cisco | Cloud Native Broadband Network Gateway | before 2025.03.1 | 2025.03.1 |
| Cisco | Inode Manager | Not specified in the record | Not stated |
| Cisco | Smart Phy | before 25.2 | 25.2 |
| Cisco | Ultra Packet Core | before 2025.03 | 2025.03 |
| Cisco | Ultra Services Platform | Not specified in the record | Not stated |
| Cisco | Staros | before 2025.03 | 2025.03 |
| Cisco | Optical Site Manager | before 25.2.1 | 25.2.1 |
| Cisco | Ncs 2000 Shelf Virtualization Orchestrator Firmware | before 25.1.1 | 25.1.1 |
| Cisco | Enterprise Nfv Infrastructure Software | before 4.18 | 4.18 |
| Cisco | Ultra Cloud Core | before 2025.03.1 | 2025.03.1 |
| Cisco | Rv160w Firmware | Not specified in the record | Not stated |
| Cisco | Rv260 Firmware | Not specified in the record | Not stated |
| Cisco | Rv160 Firmware | Not specified in the record | Not stated |
| Cisco | Rv260p Firmware | Not specified in the record | Not stated |
| Cisco | Rv260w Firmware | Not specified in the record | Not stated |
| Cisco | Rv340 Firmware | Not specified in the record | Not stated |
| Cisco | Rv340w Firmware | Not specified in the record | Not stated |
| Cisco | Rv345 Firmware | Not specified in the record | Not stated |
| Cisco | Rv345p Firmware | Not specified in the record | Not stated |
| Debian | Debian Linux | 11.0 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by CNA (github.com).
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Authentication for Critical Functionality
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
How developers prevent this class of flaw
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator.
- When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data.
More Missing Authentication for Critical Functionality vulnerabilities (CWE-306)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2025/04/msg00028.htmlThird Party Advisory
- security.netapp.com/advisory/ntap-20250425-0001/Third Party Advisory
- sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-erlang-otp-ssh-xyZZyThird Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-32433US Government Resource
Technical write-ups (may include proof of concept)
Other references
- openwall.com/lists/oss-security/2025/04/16/2Mailing List
- openwall.com/lists/oss-security/2025/04/18/1Mailing List
- openwall.com/lists/oss-security/2025/04/18/2Mailing List
- openwall.com/lists/oss-security/2025/04/18/6Mailing List
- openwall.com/lists/oss-security/2025/04/19/1Mailing List
Other vulnerabilities in otp
- 8.2 High severity
- 9.3 Critical severity
- 7.1 High severity
- 8.2 High severity
- 8.2 High severity
- 8.7 High severity
Recent Missing Authentication for Critical Functionality vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 8.2 High severity
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