CVE-2021-27889

MEDIUM 6.1CVE-2021-27889 · Published 15/03/2021 · updated 17/06/2026

In short

CVE-2021-27889 is a MEDIUM (CVSS 6.1) vulnerability affecting mybb (mybb).
Chance of exploitation in the next 30 days (EPSS): 5.1%, higher than 92.3% of all vulnerabilities.
Fix: update to 1.8.26 or later.

Package	Affected versions	Patched versions
mybb mybb	`< 1.8.26`	`1.8.26`

Cross-site Scripting (XSS) vulnerability in MyBB before 1.8.26 via Nested Auto URL when parsing messages.

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Package

Affected versions

Patched versions

< 1.8.26

1.8.26

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