Authentication bypass via signature-method confusion
Published Aug 19, 2026 · Updated Aug 19, 2026
Authentication bypass in Net::OAuth before 0.33 for Perl allows remote attackers to forge OAuth-signed requests via oauth_signature_method. Net::OAuth::Message::verify calls _signature_method_class on the untrusted message parameter and then verifies with the named algorithm, while the HMAC path derives its key from consumer_secret and token_secret rather than from the provider's configured RSA verification path. The issue is sharpest on RSA-SHA1 deployments, where a guessable placeholder consumer_secret can become the effective HMAC signing key and let forged requests pass as any consumer key and token.
Summary
What happened
Authentication bypass in Net::OAuth before 0.33 for Perl allows remote attackers to forge OAuth-signed requests via oauth_signature_method. Net::OAuth::Message::verify calls _signature_method_class on the untrusted message parameter and then verifies with the named algorithm, while the HMAC path derives its key from consumer_secret and token_secret rather than from the provider's configured RSA verification path. The issue is sharpest on RSA-SHA1 deployments, where a guessable placeholder consumer_secret can become the effective HMAC signing key and let forged requests pass as any consumer key and token.
The record
- CVE
- CVE-2026-72889
- Published
- Aug 19, 2026
- Updated
- Aug 19, 2026
- Vendor
- Net-OAuth Project
- Product
- Net-OAuth
- Classifications
- CWE-757, CWE-347
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 19, 2026CVE publishedPublication date reported by the CVE source.
- Aug 19, 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 <0.33
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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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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