CVE-2023-40033

Flarum is an open source forum software. Flarum is affected by a vulnerability that allows an attacker to conduct a Blind Server-Side Request Forgery (SSRF) attack or disclose any file on the server, even with a basic user account on any Flarum forum. By uploading a file containing a URL and spoofing the MIME type, an attacker can manipulate the application to execute unintended actions. The vulnerability is due to the behavior of the `intervention/image` package, which attempts to interpret the supplied file contents as a URL, which then fetches its contents. This allows an attacker to exploit the vulnerability to perform SSRF attacks, disclose local file contents, or conduct a blind oracle attack. This has been patched in Flarum version 1.8.0. Users are advised to upgrade. Users unable to upgrade may disable PHP's `allow_url_fopen` which will prevent the fetching of external files via URLs as a temporary workaround for the SSRF aspect of the vulnerability.

• CWE-918

• https://github.com/flarum/framework/commit/d1059c1cc79fe61f9538f3da55e8f42abbede570Patch
• https://github.com/flarum/framework/security/advisories/GHSA-67c6-q4j4-hccgVendor Advisory
• https://github.com/flarum/framework/commit/d1059c1cc79fe61f9538f3da55e8f42abbede570Patch
• https://github.com/flarum/framework/security/advisories/GHSA-67c6-q4j4-hccgVendor Advisory

Published

Aug 16, 2023

Last Modified

Jun 17, 2026

Status

Modified

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