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Vulnerability record · CVE-2011-10018 · published 13 August 2025

CVE-2011-10018: Mybb code injection vulnerability

Mybb · Mybb

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.

10.0 CVSS 4.0 Critical EPSS 2.0% · top 20.3% CWE-94 · Code injectionCWE-912 · CWE-912
10.0CVSS 4.0 base score
2.0%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
7References, 2 tagged exploit
16 Jun 2026Last modified by NVD

Description

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.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://blog.mybb.com/2011/10/06/1-6-4-security-vulnerabilit/ Vendor Advisory
https://raw.githubusercontent.com/rapid7/metasploit-framework/master/modules/exploits/unix/webapp/mybb_backdoor.rb Product
https://web.archive.org/web/20111015224948/http://secunia.com/advisories/46300/ Third Party Advisory
https://www.exploit-db.com/exploits/17949 Exploit
https://www.vulncheck.com/advisories/mybb-backdoor-arbitrary-command-execution Third Party Advisory
https://raw.githubusercontent.com/rapid7/metasploit-framework/master/modules/exploits/unix/webapp/mybb_backdoor.rb Product
https://www.exploit-db.com/exploits/17949 Exploit

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

10.0CVE-2015-8974Mybb merge system sql injection vulnerabilitySQL injection vulnerability in the Group Promotions module in the admin control panel in MyBB (aka MyBulletinBoard) before 1.6.18 and 1.8.x before 1.…EPSS 2.1%10.0CVE-2015-2786Mybb vulnerabilityUnspecified vulnerability in MyBB (aka MyBulletinBoard) before 1.8.4 has unknown attack vectors related to "Group join request notifications sent to …EPSS 1.4%10.0CVE-2011-5133Mybb vulnerabilityUnspecified vulnerability in MyBB before 1.6.5 has unknown impact and attack vectors, related to an "unparsed user avatar in the buddy list."EPSS 1.7%10.0CVE-2006-0218Mybb vulnerabilityMultiple unspecified vulnerabilities in MyBulletinBoard (MyBB) before 1.0.2 have unspecified impact and attack vectors, related to (1) admin/moderate…EPSS 1.2%9.8CVE-2020-22612Mybb code injection vulnerabilityInstaller RCE on settings file write in MyBB before 1.8.22.EPSS 0.73%9.8CVE-2017-16780Mybb cross-site request forgery vulnerabilityThe installer in MyBB before 1.8.13 allows remote attackers to execute arbitrary code by writing to the configuration file.EPSS 5.8%9.8CVE-2016-9402Mybb merge system sql injection vulnerabilitySQL injection vulnerability in the moderation tool in MyBB (aka MyBulletinBoard) before 1.8.7 and MyBB Merge System before 1.8.7 might allow remote a…EPSS 2.1%9.8CVE-2016-9403Mybb merge system permissions and access controls vulnerabilitynewreply.php in MyBB (aka MyBulletinBoard) before 1.8.7 and MyBB Merge System before 1.8.7 allows remote attackers to have unspecified impact by leve…EPSS 2.6%

Source: NIST National Vulnerability Database (record CVE-2011-10018), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.