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CVE-2021-26918

9.8 · CRITICAL

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…

Published Feb 9, 2021CWE-434EPSS 2.58%

Overview

CVE-2021-26918 is a critical-severity vulnerability. It was published on February 9, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refpacketstormsecurity.com/files/161347/Discord-Probot-Arbitrary-File-Upload.htmlRefraw.githubusercontent.com/TheLastVvV/Vulnerability-Reports-and-CVE/main/Reports/Discord%20Probot%20-%20Unrestricted%20File%20Upload.txtRefpacketstormsecurity.com/files/161347/Discord-Probot-Arbitrary-File-Upload.htmlRefraw.githubusercontent.com/TheLastVvV/Vulnerability-Reports-and-CVE/main/Reports/Discord%20Probot%20-%20Unrestricted%20File%20Upload.txt

How CyberStrike helps

Frequently asked questions

What is CVE-2021-26918?

CVE-2021-26918 is a critical-severity vulnerability. It was published on February 9, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2021-26918?

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-26918?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-26918?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-26918 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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