$ cve CVE-2021-26918 JSON

CVE-2021-26918

9.8

CRITICAL · CVSS 3.1 · EPSS 2.6% (pctl 85)

In your normal cycle

Critical by CVSS (9.8), but no sign of active exploitation.

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.

Scoring

CVSS	9.8 (CRITICAL, v3.1)
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS	2.59% — more likely to be exploited than 85% of all CVEs
Weakness	CWE-434
On CISA KEV	no
Public exploit	none known
Published	2021-02-09
Last modified	2026-06-17

Affected (1)

Vendor	Product
probot	bot

References

→ the Explorer · watch your stack · NVD