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

CVE-2021-27889

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

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

MEDIUM · CVSS 6.1 EPSS 0.00962
Schedule remediation
  • Public exploit or PoC is available
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
▤

Affected Products & Versions

1
mybb< 1.8.26
⚠

Public Exploits & PoCs

3
webappsMyBB 1.8.25 - Chained Remote Command Execution2021-03-22
pocpacketstormsecurity.com · MyBB-1.8.25-Remote-Command-Execution.htmlpacketstormsecurity.com
pocblog.sonarsource.com · mybb-remote-code-execution-chainblog.sonarsource.com
▣

Scoring & Timeline

6.1
MEDIUM · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD15 Mar 2021 · 05:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/mybb/mybb/security/advisories/GHSA-xhj7-3349-mqcmPatchThird Party Advisory
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