What’s Vulnerable › Vulnerabilities

CVE-2021-22886

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-03-26 · updated 2026-06-17
• Weakness: CWE-79

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.

Affected products

• Rocket.Chat: before 3.8.8; from 3.9.0 before 3.9.7; from 3.10.0 before 3.10.5; 3.11.0-rc0, 3.11.0-rc1, 3.11.0-rc2, 3.11.0-rc3, 3.11.0-rc4, 3.11.0-rc5 (+2) — fixed in 3.10.5, 3.8.8, 3.9.7

How to fix

Upgrade to a fixed version: Rocket.Chat 3.10.5, 3.8.8, 3.9.7. Check the vendor advisory for mitigations.

References

• https://docs.rocket.chat/guides/security/security-updates
• https://github.com/RocketChat/Rocket.Chat/pull/20430
• https://hackerone.com/reports/1014459
• https://docs.rocket.chat/guides/security/security-updates
• https://github.com/RocketChat/Rocket.Chat/pull/20430
• https://hackerone.com/reports/1014459

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