Mastodon, a popular free open-source social network server based on ActivityPub, has recently been discovered to have a security vulnerability. Attackers with carefully crafted media files can create and overwrite any file that Mastodon has access to, allowing Denial of Service (DoS) and arbitrary Remote Code Execution (RCE). In this post, we will explore and explain the details surrounding the vulnerability, references, and mitigation steps for affected software versions.

CVE-2023-36460 specifically affects versions 3.5. and prior, up to versions 3.5.9, 4..5, and 4.1.3 of Mastodon. The issue lies within the media processing code, which can be exploited by attackers who create carefully crafted media files. The ability to create arbitrary files at any location allows attackers to perform a DoS attack or execute arbitrary code remotely.

Here's a code snippet illustrating the vulnerability

# assume malicious_image.jpeg contains crafted content intended for exploitation
with open("malicious_image.jpeg", "rb") as file:
    data =

# Mastodon processes the image and the malicious payload

# At this point, attacker controls file creation and can potentially overwrite critical Mastodon files

Original references to this vulnerability can be found at Mastodon GitHub Repository, where the issue was acknowledged and patched in versions 3.5.9, 4..5, and 4.1.3.

For users running vulnerable versions of Mastodon (3.5. and prior), it is highly recommended to upgrade to the latest patched versions (3.5.9, 4..5, or 4.1.3) to mitigate the risk of CVE-2023-36460 exploitation. The process of upgrading Mastodon can be found in the official documentation.

In conclusion, the CVE-2023-36460 vulnerability poses a significant security risk to Mastodon installations, enabling attackers to perform DoS attacks and execute arbitrary code remotely. All Mastodon users are urged to upgrade to the patched versions as soon as possible to protect their systems from potential attacks. Stay vigilant and ensure the security of your systems by keeping up to date with patches and security updates.


Published on: 07/06/2023 19:15:00 UTC
Last modified on: 07/14/2023 19:31:00 UTC