CVE-2025-57320: 
JavaScript vulnerability analysis and mitigation

CVE-2025-57320 is a Prototype Pollution vulnerability in the json-schema-editor-visual npm package (also known as json-schema-editor-vue), affecting versions up to and including 1.1.1 (GitHub Advisory notes affected versions as <= 2.0.0). The flaw resides in the setData and deleteData functions, allowing unauthenticated remote attackers to inject or delete properties on Object.prototype via crafted payloads. It was published on September 24, 2025, with the GitHub Advisory reviewed on September 26, 2025. The vulnerability carries a CVSS v3.1 base score of 6.5 (Medium) (Github Advisory).

The root cause is classified as CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes — 'Prototype Pollution'). The setData and deleteData utility functions in the package fail to sanitize user-supplied property paths before using them in object manipulation operations, allowing attackers to traverse the prototype chain using special keys such as __proto__ and toString. By supplying a crafted payload with nested property references, an attacker can modify or delete properties on Object.prototype, which is shared across all JavaScript objects in the runtime. The attack vector is network-based, requires no privileges or user interaction, and a public PoC is available on GitHub (Github Advisory, PoC Repo).

Successful exploitation can corrupt the shared Object.prototype, causing denial of service (DoS) as the minimum consequence — potentially crashing or destabilizing any Node.js application that relies on the affected package. Beyond DoS, prototype pollution can lead to unexpected application behavior, logic bypasses, or in some contexts, remote code execution depending on how the polluted properties are subsequently consumed by the application. The vulnerability also carries a low confidentiality impact, suggesting potential for limited information disclosure (Github Advisory).

A public proof-of-concept (PoC) is available in the VulnSageAgent/PoCs GitHub repository, demonstrating exploitation of the setData and deleteData functions (PoC Repo). There is no current evidence of active in-the-wild exploitation or threat actor attribution. The EPSS score is approximately 0.133% (32nd percentile), indicating a low but non-negligible probability of exploitation within 30 days. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog (Github Advisory).

1. Identify target: Locate a Node.js application that uses json-schema-editor-visual version <= 1.1.1 (or <= 2.0.0 per GitHub Advisory) and exposes schema editing functionality to user input.
2. Craft malicious payload: Construct a JSON payload that uses prototype-polluting keys such as __proto__ or constructor.prototype as property path segments — for example: {"__proto__": {"polluted": true}}.
3. Trigger vulnerable function: Submit the crafted payload to an endpoint or UI component that internally calls the setData or deleteData functions of the package during schema processing.
4. Achieve prototype pollution: The insufficient path validation allows the payload to traverse the prototype chain and set or delete properties on Object.prototype, affecting all objects in the JavaScript runtime.
5. Observe impact: Depending on the application, this may result in DoS (application crash or instability), logic bypass, or further exploitation if polluted properties are used in security-sensitive operations (PoC Repo, Github Advisory).

• Network: Unusual or malformed JSON payloads submitted to schema editor endpoints containing keys such as __proto__, constructor, or prototype in property paths.
• Logs: Application error logs showing unexpected property access or type errors on standard JavaScript objects; Node.js runtime exceptions related to prototype chain corruption.
• Process: Unexpected application crashes or restarts of Node.js processes hosting the affected package; anomalous behavior in object property lookups across the application.
• File System: Presence of PoC scripts (e.g., index.js from the VulnSageAgent PoC repository) on the server filesystem if an attacker has achieved further access (PoC Repo).

No patched version of json-schema-editor-visual has been officially released as of the advisory publication — the GitHub Advisory notes no patched versions and affected versions as <= 2.0.0. Organizations should implement input validation to reject property paths containing __proto__, constructor, or prototype keys before passing data to setData or deleteData functions. Using Object.freeze(Object.prototype) in the application can prevent runtime prototype modifications as a defensive measure. Monitoring for and removing or replacing the dependency with a maintained alternative is strongly recommended (Github Advisory).

Red Hat has published a security advisory tracking this CVE, indicating awareness among enterprise Linux vendors (Red Hat Advisory). GitLab's advisory database has also indexed the vulnerability for the npm package. No significant researcher commentary or broad media coverage has been identified beyond standard vulnerability database entries.