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TI-2021-08819 Aliases CVE-2021-27279

MyBB before 1.8.25 allows stored XSS via nested [email] tags with MyCode (aka BBCode).

Priority LOW 26CWE-79Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
Required
Attack complexity
Low
Impact type
Cross-site scripting
Confidentiality · integrity · availability
Low · Low · None
Fix status
No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-79.

Summary

MyBB before 1.8.25 allows stored XSS via nested [email] tags with MyCode (aka BBCode).

Why it matters now

EPSS 0.00959 61st percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:mybb:mybb:*:*:*:*:*:*:*:*before 1.8.25Vulnerablemybb
  • cpe:2.3:a:mybb:mybb:*:*:*:*:*:*:*:* Versions before 1.8.25 Vulnerable ·mybb

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-27279

References

  • TI-2011-04621 myBB 1.6.4 Backdoor Arbitrary Command Execution CVSS 4.0CRITICAL 10.0
  • TI-2022-08548 Remote code execution in mybb CVSS 3.1HIGH 7.2
  • TI-2023-21959 MyBB before 1.8.36 allows Code Injection by users with certain high privileges. CVSS 3.1HIGH 7.2
  • TI-2022-18641 Mail settings' command parameter injection in mybb CVSS 3.1HIGH 7.2
  • TI-2025-21092 An issue in MyBB 1.8.38 allows a remote attacker to obtain sensitive information via the… CVSS 3.1HIGH 7.6
  • TI-2025-21091 An issue in MyBB 1.8.38 allows a remote attacker to obtain sensitive information via the… CVSS 3.1HIGH 7.6
See all 139 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences