CVE-2021-22886

Name: CVE-2021-22886
Creator: NVD / NIST
Published: 2021-03-26T19:15:11.913+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 1.70%

Last modified Jun 17, 2026

CVE-2021-22886 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. Rocket.Chat before 3.11, 3.10.5, 3.9.7, 3.8.8 is vulnerable to persistent cross-site scripting (XSS) using nested markdown tags allowing a remote attacker to inject arbitrary JavaScript in a message. This flaw leads to arbitrary file read and RCE on Rocket.Chat desktop app.. EPSS estimates a 1.70% chance of exploitation in the next 30 days.

Description

Rocket.Chat before 3.11, 3.10.5, 3.9.7, 3.8.8 is vulnerable to persistent cross-site scripting (XSS) using nested markdown tags allowing a remote attacker to inject arbitrary JavaScript in a message. This flaw leads to arbitrary file read and RCE on Rocket.Chat desktop app.

Metrics

CVSS 3.1

6.1/10

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

EPSS Probability

1.70%

74.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Rocket.Chat	Rocket.Chat	< 3.8.8	—
Rocket.Chat	Rocket.Chat	>= 3.9.0, < 3.9.7	—
Rocket.Chat	Rocket.Chat	>= 3.10.0, < 3.10.5	—
Rocket.Chat	Rocket.Chat	3.11.0	Rc0

References

https://docs.rocket.chat/guides/security/security-updatesVendor Advisory
https://github.com/RocketChat/Rocket.Chat/pull/20430Patch, Third Party Advisory
https://hackerone.com/reports/1014459Third Party Advisory
https://docs.rocket.chat/guides/security/security-updatesVendor Advisory
https://github.com/RocketChat/Rocket.Chat/pull/20430Patch, Third Party Advisory
https://hackerone.com/reports/1014459Third Party Advisory

Timeline

Published: Mar 26, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-22886?

How severe is CVE-2021-22886?

CVE-2021-22886 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 1.70% probability of exploitation in the next 30 days.

How do I fix CVE-2021-22886?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-22886?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST