CVE-2025-69873
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
Debian Mixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Affected | — |
| sid | Fixed | 8.18.0~ds+~cs6.1.1-1 |
| forky | Fixed | 8.18.0~ds+~cs6.1.1-1 |
| bullseye | Affected | — |
| bookworm | Affected | — |
References
- https://nvd.nist.gov/vuln/detail/CVE-2025-69873
- https://github.com/ajv-validator/ajv/pull/2586
- https://github.com/ajv-validator/ajv/pull/2588
- https://github.com/ajv-validator/ajv/pull/2590
- https://github.com/github/advisory-database/pull/6991
- https://github.com/ajv-validator/ajv/commit/720a23fa453ffae8340e92c9b0fe886c54cfe0d5
- https://github.com/EthanKim88/ethan-cve-disclosures/blob/main/CVE-2025-69873-ajv-ReDoS.md
- https://github.com/advisories/GHSA-2g4f-4pwh-qvx6
- https://github.com/ajv-validator/ajv
- https://github.com/ajv-validator/ajv/releases/tag/v6.14.0
- https://github.com/ajv-validator/ajv/releases/tag/v8.18.0
- https://security-tracker.debian.org/tracker/CVE-2025-69873
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.