CVE-2025-57319 is a Prototype Pollution vulnerability identified in the fast-redact package, specifically affecting versions 3.5.0 and earlier. Fast-redact is a JavaScript library designed to perform rapid object redaction, commonly used to sanitize or redact sensitive information from objects. The vulnerability resides in the nestedRestore function, which improperly handles crafted payloads that can inject or modify properties on the Object.prototype. Prototype Pollution occurs when an attacker manipulates the prototype of a base object, thereby influencing all objects inheriting from it. This can lead to unexpected behavior or security issues in applications relying on the affected library. In this case, the minimum confirmed impact is a denial of service (DoS), where the application may crash or become unresponsive due to corrupted object states. However, the supplier disputes the severity, arguing that the reporter only demonstrated access to properties via an internal utility function and that the public API does not allow exploitation to achieve prototype pollution. Despite this dispute, the CVSS score assigned is 7.5 (high severity), reflecting a network attack vector with low complexity, no privileges or user interaction required, and an impact limited to availability (denial of service). No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability was published on September 24, 2025, and remains a concern for applications that depend on fast-redact for data redaction tasks, especially in environments where untrusted input is processed.

For European organizations, the impact of this vulnerability depends largely on the adoption of the fast-redact package within their software stacks. Organizations using fast-redact in web applications, APIs, or backend services that process untrusted or external data inputs are at risk of denial of service attacks. Such attacks could disrupt critical services, leading to downtime, degraded user experience, and potential financial losses. Industries with high data sensitivity, such as finance, healthcare, and government, may face operational disruptions if their redaction processes fail or cause application crashes. Additionally, denial of service can be leveraged as a vector for further attacks or to distract security teams. Given the nature of prototype pollution, there is also a theoretical risk that future exploit techniques could escalate the impact beyond DoS, although this has not been demonstrated. The dispute by the supplier suggests that exploitation might be limited or require specific conditions, but organizations should not dismiss the risk without thorough testing. The lack of patches means organizations must proactively assess and mitigate exposure. Overall, the threat poses a moderate to high operational risk, particularly for European entities relying on JavaScript-based redaction tools in their data processing pipelines.

1. Immediate code audit: Review all usage of the fast-redact package in your codebase, focusing on versions 3.5.0 and earlier. Identify if the nestedRestore function or related internal utilities are invoked with untrusted input. 2. Input validation: Implement strict validation and sanitization of all inputs that may reach the nestedRestore function or any redaction routines to prevent crafted payloads from reaching the vulnerable code path. 3. Dependency update: Monitor the fast-redact project for official patches or newer versions that address this vulnerability. Plan to upgrade as soon as a fixed version is released. 4. Temporary workaround: If upgrading is not immediately possible, consider isolating or sandboxing components that use fast-redact to limit the impact of potential DoS conditions. 5. Monitoring and detection: Deploy runtime monitoring to detect unusual application crashes or performance degradation that may indicate exploitation attempts. 6. Security testing: Conduct penetration testing and fuzzing focused on prototype pollution vectors targeting the redaction functionality. 7. Incident response readiness: Prepare response plans for denial of service incidents, including failover strategies and communication protocols. 8. Engage with suppliers: If using third-party software that depends on fast-redact, coordinate with vendors to understand their mitigation plans and timelines.