Password-hash inference via variable-time comparison
Published Jul 20, 2026 · Updated Jul 20, 2026
Timing side channel in Crypt::Password 0.28 and earlier allows remote attackers to infer password hashes through repeated login attempts. The check_password method compares computed and stored hashes with Perl's built-in eq operator, whose input-dependent execution time exposes matching-prefix information. Exploitation requires an application to expose check_password through a remotely measurable authentication path; the issue discloses hash information without altering data or interrupting service.
Summary
What happened
Timing side channel in Crypt::Password 0.28 and earlier allows remote attackers to infer password hashes through repeated login attempts. The check_password method compares computed and stored hashes with Perl's built-in eq operator, whose input-dependent execution time exposes matching-prefix information. Exploitation requires an application to expose check_password through a remotely measurable authentication path; the issue discloses hash information without altering data or interrupting service.
The record
- CVE
- CVE-2026-6656
- Published
- Jul 20, 2026
- Updated
- Jul 20, 2026
- Vendor
- Steve Eirium
- Product
- Crypt::Password
- Classifications
- CWE-208, T1110.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 20, 2026CVE publishedPublication date reported by the CVE source.
- Jul 20, 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?
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- Affected versionversion=0 <=0.28
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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