TI-2011-04621 Aliases CVE-2011-10018 GHSA-4whv-mhhp-7qcj

myBB 1.6.4 Backdoor Arbitrary Command Execution

HIGH 82CWE-912Published 2025-08-13 · Updated 2026-04-07

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: Code execution
Confidentiality · integrity · availability: High · High · High
Fix status: No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-94.

Summary

myBB version 1.6.4 was distributed with an unauthorized backdoor embedded in the source code. The backdoor allowed remote attackers to execute arbitrary PHP code by injecting payloads into a specially crafted collapsed cookie. This vulnerability was introduced during packaging and was not part of the intended application logic. Exploitation requires no authentication and results in full compromise of the web server under the context of the web application.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.03024 87th percentileScored 2026-11-07

Public exploit Yes 2 exploit referencesTagged by the CNA and NVD

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
myBB Group	Forum Software	1.6.4	—	No fix listed	CNA

Forum Software VendormyBB Group Affected 1.6.4 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:mybb:mybb:1.6.4:::::::*	1.6.4	Vulnerable	mybb

cpe:2.3:a:mybb:mybb:1.6.4:*:*:*:*:*:*:* Versions 1.6.4 Vulnerable ·mybb

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2011-10018
2026-10-03 Alias added: GHSA-4whv-mhhp-7qcj

References

Exploit 2

Patch 1

https://blog.mybb.com/2011/10/06/1-6-4-security-vulnerabilit/

Advisory 1

https://web.archive.org/web/20111015224948/http://secunia.com/advisories/46300/

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
TI-2025-21090 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