CVE-2021-27889

medium

Description

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

References

https://github.com/mybb/mybb/security/advisories/GHSA-xhj7-3349-mqcm

https://blog.sonarsource.com/mybb-remote-code-execution-chain

http://packetstormsecurity.com/files/161908/MyBB-1.8.25-Remote-Command-Execution.html

Details

Source: Mitre, NVD

Published: 2021-03-15

Updated: 2026-06-17

Risk Information

CVSS v2

Base Score: 4.3

Vector: CVSS2#AV:N/AC:M/Au:N/C:N/I:P/A:N

Severity: Medium

CVSS v3

Base Score: 6.1

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

Severity: Medium

EPSS

EPSS: 0.04393