Code execution via unvalidated username control characters
Published Oct 6, 2025 · Updated Oct 6, 2025
Command injection in the OpenSSH ssh client before 10.1 allows attackers to execute shell commands through a crafted remote username. ssh.c's valid_ruser accepted control characters, so newline-bearing usernames from command-line or expanded configuration input reached the shell-backed ProxyCommand %r substitution. Execution requires untrusted input to construct an ssh invocation and a matching ProxyCommand that expands %r; the demonstrated path uses a recursive Git submodule clone.
Summary
What happened
Command injection in the OpenSSH ssh client before 10.1 allows attackers to execute shell commands through a crafted remote username. ssh.c's valid_ruser accepted control characters, so newline-bearing usernames from command-line or expanded configuration input reached the shell-backed ProxyCommand %r substitution. Execution requires untrusted input to construct an ssh invocation and a matching ProxyCommand that expands %r; the demonstrated path uses a recursive Git submodule clone.
The record
- CVE
- CVE-2025-61984
- Published
- Oct 6, 2025
- Updated
- Oct 6, 2025
- Vendor
- OpenBSD Project
- Product
- OpenSSH
- Classifications
- CWE-159, T1059.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Oct 6, 2025CVE publishedPublication date reported by the CVE source.
- Oct 6, 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 <10.1
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.
Weakness, pattern, technique
Public exploit references
- CVE-2025-61984 malicious Git submodule proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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