CVE-2026-13410 in Dancer::Plugin::Auth::Google
Summary
by MITRE • 07/17/2026
Dancer::Plugin::Auth::Google versions through 0.07 for Perl have TLS verification disabled.
The default user agent is initialised with SSL_verify_mode explicitly disabled.
An attacker with network man-in-the-middle (MITM) capability between the Dancer application and googleapis.com can intercept the OAuth2 token exchange and userinfo fetch, return a forged access_token and user profile, and be logged in to the Dancer application as any Google user.
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Analysis
by VulDB Data Team • 07/17/2026
The vulnerability resides in Dancer::Plugin::Auth::Google version 0.07 and earlier, where the implementation fails to enforce proper Transport Layer Security verification during communication with Google's OAuth2 endpoints. This critical flaw stems from the explicit disabling of SSL_verify_mode within the default user agent configuration, creating a dangerous trust relationship that bypasses essential certificate validation mechanisms. The vulnerability fundamentally compromises the security of the authentication flow by allowing attackers to establish fraudulent connections without proper cryptographic verification.
This technical weakness directly enables man-in-the-middle attack scenarios where malicious actors can position themselves between the Dancer application and Google's authentication servers. The absence of TLS verification means that any certificate presented by an attacker can be accepted as legitimate, regardless of whether it properly authenticates the intended server. During the OAuth2 token exchange process and subsequent userinfo retrieval operations, this vulnerability allows attackers to intercept and manipulate the communication channels.
The operational impact of this vulnerability is severe and far-reaching within the context of web application security. An attacker who successfully executes a MITM attack can intercept the sensitive OAuth2 token exchange process, forge access tokens, and retrieve fabricated user profile information. This enables unauthorized authentication within the Dancer application, allowing attackers to impersonate any Google user account without requiring legitimate credentials. The vulnerability essentially eliminates the cryptographic assurances that should protect against such attacks, undermining the entire authentication framework.
The security implications align with CWE-295, which addresses improper certificate validation in transport layer security implementations, and corresponds to ATT&CK technique T1566 for credential access through man-in-the-middle attacks. Organizations utilizing this vulnerable plugin face significant risk of unauthorized account takeovers, data breaches, and potential lateral movement within their network infrastructure. The vulnerability represents a critical failure in secure communication practices where the application assumes trust without proper verification mechanisms.
Mitigation strategies should prioritize immediate patching to versions that properly enable SSL verification, though administrators must also implement network-level protections such as DNS security extensions and certificate pinning where appropriate. Additional defensive measures include monitoring for unusual authentication patterns, implementing network segmentation, and ensuring all outbound communications properly validate server certificates. The fix requires reconfiguring the user agent to enforce proper SSL verification while maintaining compatibility with Google's authentication endpoints, addressing both the immediate vulnerability and preventing similar issues in future implementations.