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CVE-2026-45115

8.7 · HIGH

MyBB is free and open source forum software.

Published Aug 18, 2026CWE-79EPSS 0.42%

Overview

CVE-2026-45115 is a high-severity vulnerability. It was published on August 18, 2026 and has a CVSS 3.1 base score of 8.7 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.7, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical description

MyBB is free and open source forum software. Prior to 1.8.40, the Buddy/Ignore component does not sanitize usernames correctly, allowing attackers to perform JavaScript code injection through a specially crafted username. The User CP Buddy/Ignore list and the Select Buddies list in Private Messages pass usernames through htmlspecialchars_uni(), which may leave single quotes unescaped. The payload is triggered when a victim chooses Yes in Please Confirm while removing the username in usercp.php, or selects the username through the onclick handler in the xmlhttp.php Select Buddies popup. The uniquely identifying implementation details include Private Messages Select Buddies list, and unescaped single quotes. This issue is fixed in version 1.8.40.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/mybb/mybb/releases/tag/mybb_1840GitHubgithub.com/mybb/mybb/security/advisories/GHSA-p766-qqxv-rfc2Refmybb.com/versions/1.8.40

How CyberStrike helps

Frequently asked questions

What is CVE-2026-45115?

CVE-2026-45115 is a high-severity vulnerability. It was published on August 18, 2026 and has a CVSS 3.1 base score of 8.7 (HIGH).

How severe is CVE-2026-45115?

This vulnerability has a CVSS 3.1 base score of 8.7, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-45115?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-45115?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-45115 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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