MyBB up to 1.8.12 Installer cross site scripting

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.3$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic has been found in MyBB up to 1.8.12. This impacts an unknown function of the component Installer. The manipulation leads to cross site scripting. This vulnerability is listed as CVE-2017-16781. The attack may be initiated remotely. In addition, an exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in MyBB up to 1.8.12 (Content Management System) and classified as problematic. This issue affects some unknown processing of the component Installer. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. The summary by CVE is:

The installer in MyBB before 1.8.13 has XSS.

The bug was discovered 11/07/2017. The weakness was presented 11/10/2017 (Website). It is possible to read the advisory at blog.mybb.com. The identification of this vulnerability is CVE-2017-16781 since 11/10/2017. The attack may be initiated remotely. Required for exploitation is a simple authentication. It demands that the victim is doing some kind of user interaction. Technical details are unknown but a public exploit is available. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

The exploit is available at exploit-db.com. It is declared as proof-of-concept. The vulnerability was handled as a non-public zero-day exploit for at least 3 days. During that time the estimated underground price was around $0-$5k.

Upgrading to version 1.8.13 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Exploit-DB (43137). See VDB-109282 for similar entry. Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.4
VulDB Meta Temp Score: 4.3

VulDB Base Score: 3.5
VulDB Temp Score: 3.2
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 5.4
NVD Vector: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Access: Public
Status: Proof-of-Concept
Download: 🔍

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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OpenVAS ID: 870818
OpenVAS Name: MyBB Multiple Vulnerabilities
OpenVAS File: 🔍
OpenVAS Family: 🔍

Exploit-DB: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: MyBB 1.8.13

Timelineinfo

11/07/2017 🔍
11/10/2017 +3 days 🔍
11/10/2017 +0 days 🔍
11/10/2017 +0 days 🔍
11/11/2017 +1 days 🔍
09/17/2025 +2867 days 🔍

Sourcesinfo

Product: mybb.com

Advisory: blog.mybb.com
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2017-16781 (🔍)
GCVE (CVE): GCVE-0-2017-16781
GCVE (VulDB): GCVE-100-109283
scip Labs: https://www.scip.ch/en/?labs.20161013
See also: 🔍

Entryinfo

Created: 11/11/2017 09:31
Updated: 09/17/2025 20:40
Changes: 11/11/2017 09:31 (64), 12/05/2019 15:38 (5), 09/17/2025 20:40 (18)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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