EUVD-2026-62347Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Unauthenticated remote forgery bypasses signature checks (PR:N, C:H/I:H); AC:L as the highest-impact RSA-SHA1 case needs no special timing; A:N because impersonation does not affect availability.
Primary rating from Vendor (CPANSec).
CVSS VectorVendor: CPANSec
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
5DescriptionCVE.org
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.
AnalysisAI
Signature-verification bypass in the Net::OAuth Perl module before 0.33 lets a remote attacker forge valid OAuth requests for any consumer key and token by dictating which algorithm the Service Provider uses to check their signature. Because verify() resolves the signature-method class from the attacker-supplied signature_method parameter and offers no way to pin an expected method, a provider deployed on RSA-SHA1 (which holds only the consumer's public key) can be tricked into validating an HMAC-SHA1 signature against a placeholder/guessable consumer_secret. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a Service Provider that uses Net::OAuth (before 0.33) to verify() incoming OAuth 1.0 messages without pinning the signature method - which is every pre-0.33 deployment, since no pinning mechanism existed. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N, C:H/I:H/A:H = 9.8) reflects unauthenticated, remote, low-complexity forgery, and the CWE-347 root cause and vendor advisory corroborate a genuine authentication-bypass. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade to Vendor-released patch: Net::OAuth 0.33 (https://metacpan.org/release/RRWO/Net-OAuth-0.33/changes), which is a deliberate BREAKING change: verify() now croaks unless the verifying party explicitly states acceptable algorithms. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all production systems using Net::OAuth Perl module and identify currently deployed versions. …
Sign in for detailed remediation steps and compensating controls.
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