Cyber Resilience

CVE-2018-25248

MediumPublic PoC

Published: 04 April 2026

Published
04 April 2026
Modified
10 April 2026
KEV Added
—
Patch
—
CVSS Score v4 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/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
EPSS Score 0.0004 11.1th percentile
Risk Priority 10 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2018-25248 is a medium-severity Cross-site Scripting (CWE-79) vulnerability in Mybb Mybb Downloads. Its CVSS base score is 5.1 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 11.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-15 (Information Output Filtering).

Deeper analysis

CVE-2018-25248 is a persistent cross-site scripting (XSS) vulnerability, classified under CWE-79, affecting the MyBB Downloads Plugin version 2.0.3. The flaw resides in the download title field within downloads.php, where attackers can inject malicious HTML or JavaScript code. Published on 2026-04-04, it carries a CVSS v3.1 base score of 7.2 (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N), reflecting high severity due to its network accessibility, low complexity, lack of required privileges, no user interaction, and scope change.

Regular members of a MyBB forum can exploit this vulnerability by submitting a new download entry with malicious scripts embedded in the title parameter. The injected code persists and executes in the administrator's browser context when they validate the pending download via downloads.php, potentially leading to session hijacking, data theft, or further compromise of the admin account.

Advisories and related resources, including the MyBB community mod page (https://community.mybb.com/mods.php?action=view&pid=854), an Exploit-DB entry (https://www.exploit-db.com/exploits/44400), and a VulnCheck advisory (https://www.vulncheck.com/advisories/mybb-downloads-plugin-persistent-xss-via-downloads-php), provide further details on the issue and proof-of-concept exploitation. Security practitioners should consult these for mitigation guidance, such as plugin updates or input sanitization.

EU & UK References

Vulnerability details

MyBB Downloads Plugin 2.0.3 contains a persistent cross-site scripting vulnerability that allows regular members to inject malicious scripts through the download title field. Attackers can submit a new download with HTML/JavaScript code in the title parameter, which executes when administrators…

more

validate the download in downloads.php.

CWE(s)
CWE-79

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1185 Browser Session Hijacking Collection
Adversaries may take advantage of security vulnerabilities and inherent functionality in browser software to change content, modify user-behaviors, and intercept information as part of various browser session hijacking techniques.
attack.mitre.org →
T1539 Steal Web Session Cookie Credential Access
An adversary may steal web application or service session cookies and use them to gain access to web applications or Internet services as an authenticated user without needing credentials.
attack.mitre.org →
Why these techniques?

Stored XSS in public-facing MyBB plugin directly enables T1190 exploitation; malicious JS payload in admin context facilitates T1185 session hijacking and T1539 cookie theft.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

CVEs Like This One

CVE-2018-25250Same vendor: Mybb
CVE-2025-68008Shared CWE-79
CVE-2025-0817Shared CWE-79
CVE-2024-55227Shared CWE-79
CVE-2026-2072Shared CWE-79
CVE-2026-32728Shared CWE-79
CVE-2025-25169Shared CWE-79
CVE-2025-68887Shared CWE-79
CVE-2026-21290Shared CWE-79
CVE-2024-41746Shared CWE-79

Affected Assets

mybb
mybb downloads
2.0.3

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match
prevent

Requires validation of information inputs such as the download title field to block injection of malicious HTML/JavaScript by regular members.

SI-15 Information Output Filtering good match
prevent

Mandates filtering of information outputs like the download title when displayed to administrators in downloads.php to prevent execution of injected scripts.

SI-2 Flaw Remediation good match
prevent

Directs identification, testing, and deployment of fixes or patches for the specific XSS flaw in MyBB Downloads Plugin 2.0.3.

References