REDHAT-BUG-2439070: High severity npm/ajv vulnerability

Published Feb 11, 2026
·
Updated

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 Software

1 affected component
npm/ajv<=8.17.1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade ajv (Another JSON Schema Validator) to a version that resolves this vulnerability.

    Fixed in 8.17.1
  2. Configuration

    For any API using ajv dynamic schema validation, disable the $data option (set $data to false) to prevent unvalidated $data/JSON Pointer values from being passed into the JavaScript RegExp() constructor.

    ajv $data option = disable

Event History

Feb 11, 2026
Data Sourced
via Red Hat·07:01 PM
DescriptionSeverityAffected Software

Frequently Asked Questions

1

What is the severity of REDHAT-BUG-2439070?

The severity of REDHAT-BUG-2439070 is classified as critical due to its potential for Denial of Service attacks.

2

How do I fix REDHAT-BUG-2439070?

To fix REDHAT-BUG-2439070, update ajv to a version above 8.17.1 where the vulnerability is patched.

3

Which versions of ajv are affected by REDHAT-BUG-2439070?

ajv versions up to and including 8.17.1 are affected by REDHAT-BUG-2439070.

4

Does REDHAT-BUG-2439070 affect other packages besides ajv?

REDHAT-BUG-2439070 specifically affects the ajv package and does not mention any other related packages.

5

What is the nature of the vulnerability in REDHAT-BUG-2439070?

The nature of the vulnerability in REDHAT-BUG-2439070 is a Regular Expression Denial of Service (ReDoS) caused by unsafe handling of runtime data.

Contact

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