CVE-2026-72889
Low risk· EPSS 2%Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
In Net::OAuth for Perl before version 0.33, the sender can choose the signature algorithm used for verification. The signature_method parameter is required on every request, so the verifying party cannot pin the method. If a message names HMAC-SHA1 or HMAC-SHA256, the key is derived from consumer_secret and token_secret rather than from the provider's key. A provider using RSA-SHA1 holds only the consumer public key, and RFC 5849 does not use consumer_secret for that method, so the required parameter is filled with a placeholder. A client that names HMAC-SHA1 instead has its signature checked against that placeholder, so a guessable one is enough to forge requests for any consumer key and token.
Risk Assessment
An attacker can forge OAuth requests, potentially leading to unauthorized access to protected resources or data integrity compromise.
Recommendation
Update Net::OAuth to version 0.33 or later, which allows the verifying party to pin the signature algorithm.
Original NVD description (English source)
Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify. verify resolves the signature method class from the signature_method parameter of the incoming message. signature_method is required on every request, so the algorithm used to check a signature is chosen by whoever sent it, and nothing lets the verifying party pin the method instead. When a message names HMAC-SHA1 or HMAC-SHA256, the key is derived from consumer_secret and token_secret rather than from the key the provider deployed. A provider deployed on RSA-SHA1 holds only the consumer public key, and RFC 5849 does not use consumer_secret for that method, so the required parameter is filled with a placeholder. A client that names HMAC-SHA1 instead has its signature checked against that placeholder, so a guessable one is enough to forge requests for any consumer key and token.