CVE-2018-25309

MyBB Recent threads 17.0 Persistent Cross-Site Scripting

Published Apr 29, 2026 CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed

Description

MyBB Recent threads 17.0 contains a persistent cross-site scripting vulnerability that allows attackers to inject malicious scripts by creating threads with crafted subject lines. Attackers can create threads with script tags in the subject parameter to execute arbitrary JavaScript in the browsers of all users viewing the index page.

Analysis

Technical impact

MyBB Recent threads 17.0 contains a persistent cross‑site scripting vulnerability that allows malicious scripts to be injected via the thread subject field. Attackers create threads containing script tags, which are stored in the database and rendered unfiltered on the index page, enabling arbitrary JavaScript execution in the browsers of all users who view the index. The vulnerability is a stored XSS flaw (CWE‑79) that can lead to session hijacking, defacement, or data theft in the victim’s browser.

Affected Systems

The issue afflicts MyBB Recent threads, version 17.0. Users running this exact version are susceptible.

Risk and Exploitability

The CVSS score of 5.1 classifies it as medium severity. EPSS data is not available, and the vulnerability is not listed in the CISA KEV catalog. Attackers need only the ability to create new threads, which most forum users possess, making exploitation straightforward. The vulnerability is saved on the server and then displayed to all visitors of the index page, providing a broad attack surface.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

mybb

MyBB Recent threads

affected

Version	Status	Constraints
`17.0`	affected	—

Configuration 1 [-]

cpe:2.3:a:dragonexpert:recent_threads_on_index:17.0:*:*:*:*:mybb:*:*

No data.

Vendor Product Versions

Mybb

Version	Status	Scheme	Platform
`17.0`	affected	generic	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade the MyBB installation to a version where the cross‑site scripting fix has been applied.
If an upgrade is not immediately feasible, modify the thread creation logic to sanitize the subject field, e.g., by encoding or stripping HTML tags before storage.
Until a patch is applied, restrict or disable the ability to create threads from untrusted or anonymous accounts to reduce the opportunity for injection.

Generated by OpenCVE AI on April 30, 2026 at 03:48 UTC.

Tracking

Advisories

No advisories available

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Attack Requirements None

User Interaction Passive

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact Low

Subsequent System Integrity Impact Low

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Changed

Confidentiality Impact Low

Integrity Impact Low

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.261% probability within 30 days)

Exploitation poc

Automatable yes

Technical Impact partial

References

Link	Providers
https://community.mybb.com/mods.php?action=view&pid=191
https://www.exploit-db.com/exploits/44420
https://www.vulncheck.com/advisories/mybb-recent-threads-persistent-cross-site-scripting

History

May 1, 2026 7:30 PM First appearance in the feed. Affected versions updated. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Dragonexpert Dragonexpert recent Threads On Index
CPEs		cpe:2.3:a:dragonexpert:recent_threads_on_index:17.0:::::mybb::
Vendors & Products		Dragonexpert Dragonexpert recent Threads On Index

Apr 30, 2026 2:15 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Apr 29, 2026 8:00 PM Description updated. Title updated. First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		MyBB Recent threads 17.0 contains a persistent cross-site scripting vulnerability that allows attackers to inject malicious scripts by creating threads with crafted subject lines. Attackers can create threads with script tags in the subject parameter to execute arbitrary JavaScript in the browsers of all users viewing the index page.
Title		MyBB Recent threads 17.0 Persistent Cross-Site Scripting
First Time appeared		Mybb Mybb mybb
Weaknesses		CWE-79
CPEs		cpe:2.3:a:mybb:mybb:17.0:::::::*
Vendors & Products		Mybb Mybb mybb
References		https://community.mybb.com/mods.php?action=view&pid=191 https://www.exploit-db.com/exploits/44420 https://www.vulncheck.com/advisories/mybb-recent-threads-persistent-cross-site-scripting
Metrics		cvssV3_1 `{'score': 7.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N'}` cvssV4_0 `{'score': 5.1, 'vector': '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'}`