CVE-2011-10018

Mybb code injection

9.8 CRITICALPublic exploitEPSS 2.83%

Published13 Aug 2025

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 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Mybb1.6.4

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

Patch & vendor advisories

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

References

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.rbProduct
https://web.archive.org/web/20111015224948/http://secunia.com/advisories/46300/Third Party Advisory
https://www.exploit-db.com/exploits/17949Exploit
https://www.vulncheck.com/advisories/mybb-backdoor-arbitrary-command-executionThird Party Advisory

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2011-10018 being actively exploited?

CVE-2011-10018 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 2.83%.

How severe is CVE-2011-10018?

CVE-2011-10018 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 2.83% probability of exploitation.

Which products are affected by CVE-2011-10018?

Affected products include Mybb.

How do I fix CVE-2011-10018?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2011-10018 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.