CVE-2021-33439
An issue was discovered in mjs (mJS: Restricted JavaScript engine), ES6 (JavaScript version 6)....
An issue was discovered in mjs (mJS: Restricted JavaScript engine), ES6 (JavaScript version 6). There is Integer overflow in gc_compact_strings() in mjs.c.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
An issue was discovered in mjs (mJS: Restricted JavaScript engine), ES6 (JavaScript version 6). There is Integer overflow in gc_compact_strings() in mjs.c.
- Record
CVE-2021-33439- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Weakness
- CWE-190, CWE-476
- Updated
- 2026-11-02
CVE List No score
An issue was discovered in mjs (mJS: Restricted JavaScript engine), ES6 (JavaScript version 6). There is Integer overflow in gc_compact_strings() in mjs.c.
- Record
CVE-2021-33439- Updated
- 2026-11-02
EUVDEUVD-2021-20143 No score
An issue was discovered in mjs (mJS: Restricted JavaScript engine), ES6 (JavaScript version 6). There is Integer overflow in gc_compact_strings() in mjs.c.
- Record
EUVD-2021-20143- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-h6mp-42gx-78qp
An issue was discovered in mjs (mJS: Restricted JavaScript engine), ES6 (JavaScript version 6)....
An issue was discovered in mjs (mJS: Restricted JavaScript engine), ES6 (JavaScript version 6). There is Integer overflow in gc_compact_strings() in mjs.c.
- Record
GHSA-h6mp-42gx-78qp- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Weakness
- CWE-190
- Updated
- 2026-11-02
OSV
An issue was discovered in mjs (mJS: Restricted JavaScript engine), ES6 (JavaScript version 6). There is Integer overflow in gc_compact_strings() in mjs.c.
- Record
CVE-2021-33439- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-33439 is a medium vulnerability (CVSS 5.5) in Cesanta Mjs, published July 26, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.31%, the 24th percentile. No source names a fixed version.