CVE-2021-31330

Name: CVE-2021-31330
Creator: NVD / NIST
Published: 2022-05-11T18:15:22.303+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10EPSS 0.77%

Last modified Jun 17, 2026

CVE-2021-31330 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. A Cross-Site Scripting (XSS) vulnerability exists within Review Board versions 3.0.20 and 4.0 RC1 and earlier. An authenticated attacker may inject malicious Javascript code when using Markdown editing within the application which remains persistent.. EPSS estimates a 0.77% chance of exploitation in the next 30 days.

Description

A Cross-Site Scripting (XSS) vulnerability exists within Review Board versions 3.0.20 and 4.0 RC1 and earlier. An authenticated attacker may inject malicious Javascript code when using Markdown editing within the application which remains persistent.

Metrics

CVSS 3.1

5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.77%

50.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions	Update
Reviewboard	Review Board	3.0.20	—
Reviewboard	Review Board	4.0	Beta1

References

https://mattschmidt.net/2021/04/14/review-board-xss-discovered/Exploit, Third Party Advisory
https://www.reviewboard.org/docs/releasenotes/reviewboard/3.0.21/Release Notes, Vendor Advisory
https://www.reviewboard.org/docs/releasenotes/reviewboard/4.0-rc-2/Release Notes, Vendor Advisory
https://www.reviewboard.org/news/2021/04/14/review-board-3-0-21-and-4-0-rc-2-security-bug-fixes-and-docker/Release Notes, Vendor Advisory
https://mattschmidt.net/2021/04/14/review-board-xss-discovered/Exploit, Third Party Advisory
https://www.reviewboard.org/docs/releasenotes/reviewboard/3.0.21/Release Notes, Vendor Advisory
https://www.reviewboard.org/docs/releasenotes/reviewboard/4.0-rc-2/Release Notes, Vendor Advisory
https://www.reviewboard.org/news/2021/04/14/review-board-3-0-21-and-4-0-rc-2-security-bug-fixes-and-docker/Release Notes, Vendor Advisory

Timeline

Published: May 11, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31330?

How severe is CVE-2021-31330?

CVE-2021-31330 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.77% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31330?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-31330?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST