CVE-2025-69873

A flaw was found in ajv. When the $data option is enabled, the value of the pattern keyword is passed directly to the JavaScript RegExp() constructor without sufficient validation. An attacker able to supply a malicious regular expression pattern can trigger a ReDoS (Regular Expression Denial of Service), causing the application to become unresponsive and resulting in a denial of service.

To exploit this issue, the $data option must be enabled and the attacker needs to be able to send a payload with a specially crafted regular expression to the application processing the input. A 31-character payload causes approximately 44 seconds of execution, with each additional character doubling the execution time. Therefore, even a small payload can cause an application to become unresponsive and eventually result in a denial of service. Due to this reason, this flaw has been rated with an important severity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, disable the $data feature if your application does not require it. If $data must be used, implement strict validation of the input fields that are referenced by the pattern keyword to ensure they contain only expected and safe characters.