CVE-2021-31875
CRITICALCesanta MongooseOS mJS 1.26 - Heap-Based Buffer Overflow via Malformed JSON String
Title source: llmDescription
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."
References (3)
Core 3
Core References
Patch, Third Party Advisory
https://github.com/418sec/mjs/pull/2
Release Notes, Third Party Advisory
https://github.com/cesanta/mjs/releases/tag/1.26
Exploit, Third Party Advisory
https://huntr.dev/bounties/1-other-mjs/
Scores
CVSS v3
9.8
EPSS
0.0217
EPSS Percentile
79.9%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Details
CWE
CWE-193
CWE-787
Status
published
Products (1)
cesanta/mongooseos_mjs
1.26
Published
Apr 29, 2021
Tracked Since
Feb 18, 2026