Unauthenticated root login via injected USER argument
Published Jan 21, 2026 · Updated Jan 21, 2026
Authentication bypass in GNU Project Inetutils 1.9.3 through 2.7 allows remote attackers to obtain a root login through telnetd. telnetd passes the client-controlled USER value as the final argument to /usr/bin/login without sanitizing option delimiters, so -f root is parsed as login's preauthentication flag. The telnetd service must be running and network-reachable, but no credentials or user interaction are required; successful exploitation grants an operating-system root session.
Summary
What happened
Authentication bypass in GNU Project Inetutils 1.9.3 through 2.7 allows remote attackers to obtain a root login through telnetd. telnetd passes the client-controlled USER value as the final argument to /usr/bin/login without sanitizing option delimiters, so -f root is parsed as login's preauthentication flag. The telnetd service must be running and network-reachable, but no credentials or user interaction are required; successful exploitation grants an operating-system root session.
The record
- CVE
- CVE-2026-24061
- Published
- Jan 21, 2026
- Updated
- Jan 21, 2026
- Vendor
- The GnuPG Project
- Product
- Inetutils
- Classifications
- CWE-88, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 21, 2026CVE publishedPublication date reported by the CVE source.
- Jan 21, 2026Record updatedLatest update available in the CVE record.
- Jan 21, 2026Exploitation reportedGreyNoise vulnerable-sensor exploitation campaign
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=1.9.3 <=2.7
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
- USER=-f root Telnet authentication-bypass examplefunctional · demonstrated
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Reported exploitation
- CISA Known Exploited Vulnerabilities listingknown exploited catalog
- GreyNoise vulnerable-sensor exploitation campaignhoneypot
Technologies
Your stack
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Your stack
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