What’s Vulnerable › Vulnerabilities

CVE-2024-23336: Incomplete disallowed remote addresses list in MyBB

• Severity: medium (CVSS 5.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-05-01 · updated 2026-06-17
• Weakness: CWE-184

Description

MyBB is a free and open source forum software. The default list of disallowed remote hosts does not contain the `127.0.0.0/8` block, which may result in a Server-Side Request Forgery (SSRF) vulnerability. The Configuration File's _Disallowed Remote Addresses_ list (`$config['disallowed_remote_addresses']`) contains the address `127.0.0.1`, but does not include the complete block `127.0.0.0/8`. MyBB 1.8.38 resolves this issue in default installations. Administrators of installed boards should update the existing configuration (`inc/config.php`) to include all addresses blocked by default. Additionally, users are advised to verify that it includes any other IPv4 addresses resolving to the server and other internal resources. Users unable to upgrade may manually add 127.0.0.0/8' to their disallowed address list.

Affected products

• mybb: before 1.8.38 — fixed in 1.8.38

How to fix

Upgrade to a fixed version: mybb 1.8.38. Check the vendor advisory for mitigations.

References

• https://docs.mybb.com/1.8/administration/configuration-file
• https://github.com/mybb/mybb/commit/d6a96019025de9149014e06b1df252e6122e5630
• https://github.com/mybb/mybb/security/advisories/GHSA-qfrj-65mv-h75h
• https://mybb.com/versions/1.8.38
• https://docs.mybb.com/1.8/administration/configuration-file
• https://github.com/mybb/mybb/commit/d6a96019025de9149014e06b1df252e6122e5630
• https://github.com/mybb/mybb/security/advisories/GHSA-qfrj-65mv-h75h
• https://mybb.com/versions/1.8.38

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