CVE-2021-47905: MyBB Delete Account Plugin 1.4 contains a cross-site scripting vulnerability in the account deletion reason in

Routine

MEDIUM 6.1DOWNGRADE

CVE-2021-47905 is a medium-severity flaw (CVSS 6.1) affecting delete account. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MyBB Delete Account Plugin 1.4 contains a cross-site scripting vulnerability in the account deletion reason input field. Attackers can inject malicious scripts that will execute in the admin interface when viewing delete account reasons.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 84%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-01-23
Last modified	2026-06-17

Publisher (CNA): VulnCheck · Vendor: mybb

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

Am I affected?

Timeline

2026-01-23 17:16 UTCPublished CVE record published
2026-06-17 04:18 UTCUpdated Record last modified

mybb delete account DOWNGRADE

Affected: 1.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.4

1. Check installed version

apt-cache policy delete-account || rpm -q delete-account || delete-account --version

2. No fixed release: DOWNGRADE to a release before 1.4 (Debian / Ubuntu)

apt-cache madison delete-account sudo apt install delete-account=<VERSION_BEFORE_1.4> sudo apt-mark hold delete-account

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

dnf --showduplicates list delete-account sudo dnf downgrade delete-account-<VERSION_BEFORE_1.4> sudo dnf versionlock add delete-account

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-2021-47905?

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

Is CVE-2021-47905 being exploited?

CVE-2021-47905 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-2021-47905 affect?

CVE-2021-47905 affects delete account. Severity is medium (CVSS 6.1). MyBB Delete Account Plugin 1.4 contains a cross-site scripting vulnerability in the account deletion reason input field. Attackers can inject malicious scripts that will execute in the admin interface when viewing delete account reasons.

How urgent is CVE-2021-47905?

Priority 30/100. Public exploit reference

References

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