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CVE-2025-69873

ajv has ReDoS when using `$data` option

Impact

ajv (Another JSON Schema Validator) through version 8.17.1 is vulnerable to Regular Expression Denial of Service (ReDoS) when the `$data` option is enabled. The pattern keyword accepts runtime data via JSON Pointer syntax (`$data` reference), which is passed directly to the JavaScript `RegExp()` constructor without validation. An attacker can inject a malicious regex pattern (e.g., `\"^(a|a)*$\"`) combined with crafted input to cause catastrophic backtracking. A 31-character payload causes approximately 44 seconds of CPU blocking, with each additional character doubling execution time. This enables complete denial of service with a single HTTP request against any API using ajv with `$data`: true for dynamic schema validation.

Affected packages

EcosystemPackageAffectedFixed in
npmajv>= 7.0.0-alpha.0, < 8.18.08.18.0

Affected products

ProductAffected versions
Ajv (Another JSON Schema Validator)
before 8.18.0

Versions were read from the advisory text. No structured product data has been published for this record yet.

Weakness classification

CWE-1333CWE-400

References