CVE-2025-48940
highpriority · track · 0EPSS 0.005 · 45 %ileEUUSEPSS · scored 2026-10-28
MyBB is free and open source forum software. Prior to version 1.8.39, the upgrade component does not validate user input properly, which allows attackers to perform local file inclusion (LFI) via a specially crafted parameter value. In order to exploit the vulnerability, the installer must be unlocked (no `install/lock` file present) and the upgrade script must be accessible (by re-installing the forum via access to `install/index.php`; when the forum has not yet been installed; or the attacker is authenticated as a forum administrator). MyBB 1.8.39 resolves this issue.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.6–7.2
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (2)
Products and version ranges known to be affected.
also known as (2)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (12)
External citations — patches, advisories, analysis.
- https://access.redhat.com/security/cve/cve-2025-48940cnnvd
- https://github.com/mybb/mybb/commit/6e6cfbd524d9101b51e1278ecf520479b64b0f00cnnvd
- https://github.com/mybb/mybb/security/advisories/GHSA-q4jv-xwjx-37cpcnnvd
- https://mybb.com/download/Patchcnnvd
- https://mybb.com/versions/1.8.39cnnvd
- https://nvd.nist.gov/vuln/detail/CVE-2025-48940cnnvd
- https://github.com/mybb/mybb/commit/6e6cfbd524d9101b51e1278ecf520479b64b0f00enisa_euvd
- https://github.com/mybb/mybb/security/advisories/GHSA-q4jv-xwjx-37cpenisa_euvd
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