CVE-2025-11065 is a vulnerability identified in the Go package github.com/go-viper/mapstructure/v2, specifically within the WeakDecode function responsible for decoding and processing fields from user-supplied data. This function is often used to map input data into Go structs, a common operation in configuration parsing and data deserialization. The flaw manifests when malformed or crafted input data triggers error messages that inadvertently include sensitive input values. These detailed error messages can leak confidential information if they are logged, displayed, or otherwise exposed in security-sensitive environments. The vulnerability is classified with a CVSS v3.1 score of 5.3 (medium severity), indicating a moderate risk. The attack vector is network-based (AV:N), with high attack complexity (AC:H), no privileges required (PR:N), but requires user interaction (UI:R). The scope is unchanged (S:U), and the impact is high on confidentiality (C:H), with no impact on integrity (I:N) or availability (A:N). This means an attacker who can induce error conditions through crafted inputs and convince a user to interact with the system may obtain sensitive data disclosures. No known exploits have been reported in the wild, and no patches or fixes are currently linked, suggesting the vulnerability is newly disclosed or under active investigation. The vulnerability is particularly relevant for applications that use mapstructure for decoding user inputs in security-critical contexts, such as configuration management, authentication, or authorization workflows, where leaked data could include secrets, tokens, or personal information.

The primary impact of CVE-2025-11065 is the unauthorized disclosure of sensitive information through error messages. This can lead to exposure of confidential data such as credentials, tokens, or personally identifiable information if the application logs or displays these error messages to unauthorized users. While the vulnerability does not affect data integrity or system availability, the confidentiality breach can facilitate further attacks like credential theft, privilege escalation, or targeted phishing. Organizations using the affected Go library in backend services, microservices, or configuration management tools are at risk, especially if error handling is not properly sanitized. The requirement for user interaction and high attack complexity somewhat limits exploitation, but in environments where user input is processed and error messages are visible, the risk remains significant. The absence of known exploits in the wild reduces immediate threat but does not eliminate future risk once exploit code becomes available. The vulnerability could undermine trust in affected applications and lead to compliance violations if sensitive data is exposed.

To mitigate CVE-2025-11065, organizations should first audit their use of the mapstructure library, particularly the WeakDecode function, to identify where user-supplied data is processed. Developers should implement strict input validation and sanitization to prevent malformed data from triggering detailed error messages. Error handling routines must be reviewed and updated to avoid including sensitive input values in error outputs, logs, or user-facing messages. Employing centralized logging with access controls can reduce exposure of sensitive logs. Until an official patch is released, consider isolating or sandboxing components that use mapstructure to limit data exposure. Monitoring for updates from the library maintainers and applying patches promptly is critical. Additionally, implement runtime detection mechanisms to flag unusual error message patterns or data leakage attempts. Educate developers and security teams about the risks of verbose error messages and enforce secure coding practices that minimize information disclosure. Finally, conduct penetration testing focused on error message analysis to identify potential leaks.