TI-2021-11866 Aliases CVE-2021-31875 GHSA-gjqw-r32j-j6wq

In mjs_json.c in Cesanta MongooseOS mJS 1.26, a maliciously formed JSON string can…

MEDIUM 46CWE-193Published 2021-04-29 · Updated 2024-08-03

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Code execution
Confidentiality · integrity · availability: High · High · High
Fix status: No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-193 and the CVSS impact.

Summary

In mjs_json.c in Cesanta MongooseOS mJS 1.26, a maliciously formed JSON string can trigger an off-by-one heap-based buffer overflow in mjs_json_parse, which can potentially lead to redirection of control flow. NOTE: the original reporter disputes the significance of this finding because "there isn’t very much of an opportunity to exploit this reliably for an information leak, so there isn’t any real security impact."

Why it matters now

EPSS 0.02174 82nd percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix No fix listed No fixed version in the sources yet

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
—	—	all versions	—	No fix listed	CNA

— Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:cesanta:mongooseos_mjs:1.26:::::::*	1.26	Vulnerable	Cesanta

cpe:2.3:a:cesanta:mongooseos_mjs:1.26:*:*:*:*:*:*:* Versions 1.26 Vulnerable ·Cesanta

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2021-31875
2026-10-03 Alias added: GHSA-gjqw-r32j-j6wq

References

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences