CVE-2024-25623: mastodon File Upload RCE — Fix

Description

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.2.7, 4.1.15, 4.0.15, and 3.5.19, when fetching remote statuses, Mastodon doesn't check that the response from the remote server has a `Content-Type` header value of the Activity Streams media type, which allows a threat actor to upload a crafted Activity Streams document to a remote server and make a Mastodon server fetch it, if the remote server accepts arbitrary user uploads. The vulnerability allows a threat actor to impersonate an account on a remote server that satisfies all of the following properties: allows the attacker to register an account; accepts arbitrary user-uploaded documents and places them on the same domain as the ActivityPub actors; and serves user-uploaded document in response to requests with an `Accept` header value of the Activity Streams media type. Versions 4.2.7, 4.1.15, 4.0.15, and 3.5.19 contain a fix for this issue.

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CVSS v3.1 Score

8.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:N

Weakness Type (CWE)

CWE-434 Unrestricted Upload

Affected Products

Vendor	Product	Versions
joinmastodon	mastodon	< 3.5.19
joinmastodon	mastodon	4.0.0 — 4.0.15
joinmastodon	mastodon	4.1.0 — 4.1.15
joinmastodon	mastodon	4.2.0 — 4.2.7

References

Advisories & Patches

https://github.com/mastodon/mastodon/commit/9fee5e852669e26f970e278021302e1a203fc022 https://github.com/mastodon/mastodon/security/advisories/GHSA-jhrq-qvrm-qr36 https://github.com/mastodon/mastodon/commit/9fee5e852669e26f970e278021302e1a203fc022 https://github.com/mastodon/mastodon/security/advisories/GHSA-jhrq-qvrm-qr36

Frequently Asked Questions

What is CVE-2024-25623? +

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.2.7, 4.1.15, 4.0.15, and 3.5.19, when fetching remote statuses, Mastodon doesn't check that the response from the remote server has a `Content-Type` header value of the Activity Streams media type, which allows a threat actor to upload a crafted Activity Streams document to a remote server and make a Mastodon server fetch it, if the remote server accepts arbitrary user uploads. The vulnerability allows a threat actor to impersonate an account on a remote server that satisfies all of the following properties: allows the attacker to register an account; accepts arbitrary user-uploaded documents and places them on the same domain as the ActivityPub actors; and serves user-uploaded document in response to requests with an `Accept` header value of the Activity Streams media type. Versions 4.2.7, 4.1.15, 4.0.15, and 3.5.19 contain a fix for this issue. It has a CVSS v3.1 base score of 8.5 (HIGH).

How severe is CVE-2024-25623? +

CVE-2024-25623 has a CVSS v3.1 score of 8.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2024-25623? +

CVE-2024-25623 affects products from joinmastodon, specifically: mastodon. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2024-25623? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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