CVE-2021-42136A stored Cross-Site Scripting (XSS) vulnerability in the Missing Data Codes functionality of REDCap before 11.4.0 allows remote attackers…
- 9.0CriticalCVSS base score
- 4.7%Exploitation in 30 daysEPSS · top 8.1% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- 1Public exploitsMetasploit, Nuclei and Exploit-DB
Description
A stored Cross-Site Scripting (XSS) vulnerability in the Missing Data Codes functionality of REDCap before 11.4.0 allows remote attackers to execute JavaScript code in the client's browser by storing said code as a Missing Data Code value. This can then be leveraged to execute a Cross-Site Request Forgery attack to escalate privileges to administrator.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. The public collections list an Exploit-DB entry for it.
Show the exploits1
Exploit-DB1 entry
- REDCap 11.3.9 - Stored Cross Site Scripting (Exploit-DB entry) (opens in a new tab)
EDB-ID 50877webapps, phppublished 19 Apr 2022Not verified
Modules, templates and exploits as listed by the Metasploit Framework (BSD-3-Clause), ProjectDiscovery's Nuclei templates (MIT) and the Exploit Database (GPLv2), read once a day. Where the data comes from
Timeline
ID reserved
By mitre
- 6 months later
· 6 months later
Published
- 2 years later
· 2 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Critical9.0 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 4.7% · top 8.1% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.0.
Affected products
n/a
- affected n/a
References
References3
- https://www.project-redcap.org/ (opens in a new tab)x_refsource_MISCx_transferred
- https://redcap.med.usc.edu/_shib/assets/ChangeLog_Standard.pdf (opens in a new tab)x_refsource_MISCx_transferred
- http://packetstormsecurity.com/files/166723/REDCap-Cross-Site-Scripting.html (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2021-29119 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2021-42136)Record last updated .