High

Flarum vulnerable to LFI and Blind SSRF via Avatar upload

  • Disclosed: 16.08.2023
  • Updated: 11.10.2026 10:22

Impact

The Flarum forum software is affected by a vulnerability that allows an attacker to conduct a Blind 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.

Patches

This has been patched in Flarum v1.8.

Workarounds

As a temporary workaround for the SSRF aspect of the vulnerability, one can disable PHP's allow_url_fopen which will prevent the fetching of external files via URLs.

Credits

Adam Kues - Assetnote

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Composer package flarum/core < 1.8.0 1.8.0
Composer package flarum/framework < 1.8.0 1.8.0

References

CVSS score 7.1/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness (CWE)
CWE-918, CWE-98
Platform
Composer
Package
flarum/core, flarum/framework
Disclosed
16.08.2023
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-67c6-q4j4-hccg - CC BY 4.0

Vulnerability history: flarum/core

All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (9) in the archive
Total entries
9
First → latest
06.2021 04.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 2
  • High 1
  • Medium 5
  • Low 1

Disclosures per year

  1. 2021: 1
  2. 2022: 1
  3. 2023: 4
  4. 2024: 1
  5. 2025: 1
  6. 2026: 1
Severity:
  1. Flarum vulnerable to LFI and Blind SSRF via Avatar upload this entry
    High · 7.1 CVE-2023-40033 < 1.8.0 1.8.0
  2. Critical · 9.0 CVE-2022-41938 >= 1.5.0, < 1.6.2 1.6.2
  3. Critical · 10.0 CVE-2021-32671 >= 1.0.0, < 1.0.2 1.0.2

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