CVE-2021-31684 is a high-severity (CVSS 7.5) Out-of-bounds Write vulnerability in net.minidev:json-smart. 1 public exploit reference exists, so weaponization risk is real. A fix is available for net.minidev:json-smart — see the affected versions and patch details below.
Out of bounds read in json-smart
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2021-31684.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-31684 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
net.minidev:json-smart☕net.minidev:json-smartReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
A vulnerability was discovered in the indexOf function of JSONParserByteArray in JSON Smart versions prior to 1.3.3 and 2.4.5 which causes a denial of service (DOS) via a crafted web request.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | net.minidev:json-smart | ≥ 1.3.0&&< 1.3.3 | 1.3.3net.minidev:json-smart:1.3.3 |
| ☕Maven | net.minidev:json-smart | ≥ 2.4.0&&< 2.4.4 | 2.4.4net.minidev:json-smart:2.4.4 |
Affected Products
json-smart-v1json-smart_projectjson-smart-v2json-smart_projectutilities frameworkoracleResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for net.minidev:json-smart, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update net.minidev:json-smart to 1.3.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-31684 is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Fuse 7.11.1 | json-smart | RHSA-2022:8652 |
Frequently Asked Questions
Is CVE-2021-31684 in your dependencies?
Find it across Maven, including transitive dependencies.