Password recovery via nonconstant-time plaintext comparison
Published Jun 14, 2026 · Updated Jun 14, 2026
Observable timing discrepancy in Linux-PAM through 1.7.2 allows attackers to recover plaintext passwords through repeated authentication. pam_userdb compares plaintext candidates with strncmp or strncasecmp after checking length, making rejection time reveal password length and matching prefix bytes. Exposure requires a calling service that uses pam_userdb with crypt=none, an unrecognized crypt method, or no crypt argument and permits repeated attempts.
Summary
What happened
Observable timing discrepancy in Linux-PAM through 1.7.2 allows attackers to recover plaintext passwords through repeated authentication. pam_userdb compares plaintext candidates with strncmp or strncasecmp after checking length, making rejection time reveal password length and matching prefix bytes. Exposure requires a calling service that uses pam_userdb with crypt=none, an unrecognized crypt method, or no crypt argument and permits repeated attempts.
The record
- CVE
- CVE-2026-54411
- Published
- Jun 14, 2026
- Updated
- Jun 14, 2026
- Vendor
- Linux-PAM Project
- Product
- Linux-PAM
- Classifications
- CWE-208, T1110.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 14, 2026CVE publishedPublication date reported by the CVE source.
- Jun 14, 2026Record 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 <=1.7.2
What conditions does exploitation require?
What is affected?
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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