VulnerabilityDeferred

CVE-2025-69873

ajv (Another JSON Schema Validator) before 8.18.0 is vulnerable to Regular Expression Denial of Service (ReDoS) when the $data option is enabled.

LOW 2.9EPSS 0.55%

Does this matter?

Lower severity and a low EPSS score (0.55%). Track it; it rarely justifies an emergency change on its own.

Description

ajv (Another JSON Schema Validator) before 8.18.0 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. This issue is also fixed in version 6.14.0.

CVSS 3.1: 2.9 LOWCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS: 0.55% probability · 46th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-1333, CWE-400
Source: cve@mitre.org

EPSS trend

EPSS 0.5% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.