Arbitrary file upload in Probot Bot
CVE-2021-26918
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.
Vulnerability class: Unrestricted File Upload
EPSS: 0.026 (83.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Probot Bot
- N/a — versions n/a
Weakness classification (CWE)
References
- cve@mitre.org (Exploit, Third Party Advisory, x_refsource_MISC)
- cve@mitre.org (Exploit, VDB Entry, Third Party Advisory, x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-26918?
- CVE-2021-26918 is a critical-severity vulnerability in Probot Bot, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2021-02-09.
- How severe is CVE-2021-26918?
- Critical severity. CVSS v3 base score is 9.8 out of 10.