CVE-2021-20088 json
mootools-more vulnerable to prototype pollution
published 2021-04-23 5 y ago modified 2026-06-17 4 mo ago also GHSA-fw45-938v-p26j , EUVD-2022-3844
- cvss
- 8.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.4%
- EPSS 1.4% chance of exploitation in 30 days, percentile 73%
- public exploits
- 0
- none known
Summary
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in mootools-more 1.6.0 allows a malicious user to inject properties into Object.prototype.
Exploit prediction
1.45% chance of exploitation in the next 30 days, higher than 73% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/BlackFan/client-side-prototype-pollution/blob/master/pp/mootools-more.md referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 6.5 | AV:N/AC:L/Au:S/C:P/I:P/A:P |
| GitHub | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | mootools-more | <=1.6.0 |
no fix listed |
Affected products
- n/a mootools-more
Classification
- Weakness
-
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes
References
-
github.com
/BlackFan/client-side-prototype-pollution/blob/master/pp/mootools-more.md
web, exploit, third-party-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2021-20088
advisory
-
github.com
/mootools/mootools-more
package
Sources
- CVE List CVE-2021-20088
- GitHub Advisory GHSA-fw45-938v-p26j
- NVD CVE-2021-20088
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.