# CVE-2026-72889

## Summary

- **CVE ID:** CVE-2026-72889
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-347, CWE-757
- **Published:** Aug 19, 2026
- **Last Modified:** Aug 26, 2026

## Description

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.

## Affected Products

- Unknown product (0)

## References

- [CNA](https://github.com/vurtdev/Net-OAuth/security/advisories/GHSA-c8rm-g5cm-4pf5)
- [CNA](https://github.com/vurtdev/Net-OAuth/commit/c467adf45c8d77ac4b92ad78b3eebf949252ba7f.patch)
- [CNA](https://metacpan.org/release/RRWO/Net-OAuth-0.33/changes)
- [CNA](https://datatracker.ietf.org/doc/html/rfc5849#section-3.4.2)
- [CNA](https://datatracker.ietf.org/doc/html/rfc5849#section-3.4.3)
- [CVE](http://www.openwall.com/lists/oss-security/2026/08/19/2)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.35%
- **EPSS Percentile:** 27.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._