What is CVE-2025-67221?

CVE-2025-67221 is a high-severity vulnerability in Ijl Orjson, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-01-22.

How severe is CVE-2025-67221?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2025-67221 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Resource exhaustion in Ijl Orjson

CVE-2025-67221

The orjson.dumps function in orjson thru 3.11.4 does not limit recursion for deeply nested JSON documents.

Published 2026-01-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.006 (48.8th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 48.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: +0.001

Affected products

Ijl Orjson

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

Public proof-of-concept exploits

kpatsakis/CVE-2025-67221

References

github.com/kpatsakis/orjson_vulnerability (Exploit, Third Party Advisory)
github.com/ijl/orjson (Product)

Frequently asked questions

What is CVE-2025-67221?: CVE-2025-67221 is a high-severity vulnerability in Ijl Orjson, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-01-22.
How severe is CVE-2025-67221?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2025-67221 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.