Vulnerability · Published Feb 9, 2021 · Assigned by mitre
CVE-2021-26918
Critical 9.8
In plain English
A critical-severity unrestricted file upload in the affected software. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 2.6% (higher than 86% of all known vulnerabilities).
Official description
The ProBot bot through 2021-02-08 for Discord might allow attackers to interfere with the intended purpose of the "Send an image when a user joins the server" feature (or possibly have unspecified other impact) because the uploader web service allows double extensions (such as .html.jpg) with the text/html content type. NOTE: there may not be cases in which an uploader web service is customer controlled; however, the nature of the issue has substantial interaction with customer controlled configuration. NOTE: the vendor states "This is just an uploader (like any other one) which uploads files to cloud storage and accepts various file types. There is no kind of vulnerability and it won't compromise either the client side or the server side.
Affected products (as reported)
Weakness: CWE-434 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H