CVE-2021-31330: A Cross-Site Scripting (XSS) vulnerability exists within Review Board versions 3.0.20 and 4.0 RC1 and earlier

Routine

MEDIUM 5.4DOWNGRADE

CVE-2021-31330 is a medium-severity flaw (CVSS 5.4) affecting review board. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.8% (top 43%)
CISA exploited list	No
Weakness	CWE-79
Published	2022-05-11
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: reviewboard

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-05-11 18:15 UTCPublished CVE record published
2026-06-17 03:51 UTCUpdated Record last modified

reviewboard review board DOWNGRADE

Affected: 3.0.20 · 4.0 beta1 · 4.0 beta2 · 4.0 rc1

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.0.20

1. Check installed version

apt-cache policy review-board || rpm -q review-board || review-board --version

2. No fixed release: DOWNGRADE to a release before 3.0.20 (Debian / Ubuntu)

apt-cache madison review-board sudo apt install review-board=<VERSION_BEFORE_3.0.20> sudo apt-mark hold review-board

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list review-board sudo dnf downgrade review-board-<VERSION_BEFORE_3.0.20> sudo dnf versionlock add review-board

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-31330?

review board: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-31330 being exploited?

CVE-2021-31330 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-31330 affect?

CVE-2021-31330 affects review board. Severity is medium (CVSS 5.4). 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 p

How urgent is CVE-2021-31330?

Priority 38/100. Public exploit reference

References

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