CVE-2011-10018Public exploitNetwork attack vector

Unauthenticated PHP execution via collapsed cookie

Published Aug 13, 2025 · Updated Apr 7, 2026

Code injection in MyBB 1.6.4 allows remote attackers to execute arbitrary PHP through a crafted collapsed cookie sent to index.php. The unauthorized root index.php backdoor treats PHP appended after 23 pipe-delimited cookie values as executable code without validation. No authentication or user interaction is required, and execution occurs with the web application's permissions, exposing its data and host-accessible resources.

CVSS severity10.0
Critical
EPSS probability1.98%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Code injection in MyBB 1.6.4 allows remote attackers to execute arbitrary PHP through a crafted collapsed cookie sent to index.php. The unauthorized root index.php backdoor treats PHP appended after 23 pipe-delimited cookie values as executable code without validation. No authentication or user interaction is required, and execution occurs with the web application's permissions, exposing its data and host-accessible resources.

The record

CVE
CVE-2011-10018
Published
Aug 13, 2025
Updated
Apr 7, 2026
Vendor
MyBB Group
Product
MyBB
Classifications
CWE-94, CWE-912, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 13, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.6.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MyBB Group · MyBBversion=1.6.4

Published CVSS scores

10.0VulnCheckCVSS: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:X/V:X/RE:X/U:X
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
CWE-912Hidden Functionality
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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