SSH traffic interception via default weak ciphers
Published Mar 8, 2022 · Updated Aug 12, 2025
Inadequate encryption in Siemens RUGGEDCOM ROS before 4.3.8 or 5.7.0 allows man-in-the-middle attackers to read and alter SSH traffic. The device SSH server offers weak key-exchange ciphers by default instead of restricting negotiation to the stronger supported algorithms. Exploitation requires an adjacent attacker positioned between a legitimate SSH client and the device; intercepted sessions can lose confidentiality and integrity.
Summary
What happened
Inadequate encryption in Siemens RUGGEDCOM ROS before 4.3.8 or 5.7.0 allows man-in-the-middle attackers to read and alter SSH traffic. The device SSH server offers weak key-exchange ciphers by default instead of restricting negotiation to the stronger supported algorithms. Exploitation requires an adjacent attacker positioned between a legitimate SSH client and the device; intercepted sessions can lose confidentiality and integrity.
The record
- CVE
- CVE-2021-37209
- Published
- Mar 8, 2022
- Updated
- Aug 12, 2025
- Vendor
- Siemens
- Product
- RUGGEDCOM RSG2288
- Classifications
- CWE-326, T1557
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 8, 2022CVE publishedPublication date reported by the CVE source.
- Aug 12, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <V4.3.8
- Affected versionversion=0 <V5.7.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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