Net::OAuth::Client up to 0.31 Token Exchange get_request_token oauth_verifier session fixiation

Summaryinfo

A vulnerability classified as critical was found in Net::OAuth::Client up to 0.31. The affected element is the function get_request_token of the component Token Exchange. The manipulation of the argument oauth_verifier results in session fixiation. This vulnerability was named CVE-2026-72887. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as critical, was found in Net::OAuth::Client up to 0.31. Affected is the function get_request_token of the component Token Exchange. The manipulation of the argument oauth_verifier with an unknown input leads to a session fixiation vulnerability. CWE is classifying the issue as CWE-384. Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Net::OAuth::Client versions before 0.32 for Perl allow the service provider to silently downgrade OAuth 1.0a to OAuth 1.0 in get_request_token. Passing a callback to the constructor selects OAuth 1.0a. get_request_token then revokes that choice when the request token response omits oauth_callback_confirmed, with no exception, no warning and no option to require 1.0a. The access token request is built from the OAuth 1.0 message class, which has no verifier parameter, so oauth_verifier is dropped from the request even when get_access_token was passed one. oauth_verifier is the binding that OAuth 1.0a added between the authorization step and the token exchange. An application that asked for 1.0a and gets 1.0 is open to OAuth 1.0 session fixation, where an attacker obtains a request token, has the victim authorize it, and then completes the exchange themselves, linking the victim's provider account to a session the attacker controls. No attacker action sets up the downgrade: a provider that does not confirm the callback is enough.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-72887 since 08/10/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 335909 (Linux Distros Unpatched Vulnerability : CVE-2026-72887), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 0.32 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (335909). Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

• Net::OAuth::Client

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26
• 0.27
• 0.28
• 0.29
• 0.30
• 0.31

CPE 2.3info

• 🔒
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• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

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Entryinfo

Once again VulDB remains the best source for vulnerability data.

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