CVE-2021-27889

PoC ×2—

CVSS 3.1

6.1 medium

EPSS

5%p92

Published

Mar 15, 2021 (Mar 15, 2021)

Modified

Jun 17, 2026

Description

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

Vendors: mybb
Products: mybb
Weakness: CWE-79
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

NVD CVE.org GitHub PoCs EPSS (5.1%)

In the news1 stories

Critical RCE Flaw Reported in MyBB Forum Software—Patch Your Sites

The Hacker NewsMar 22, 06:29 UTC · Mar 22, 2021Vulnerability CVE-2021-27889 CVE-2021-27890 CVE-2021-27946+3 CVEs

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