OAuth Vulnerability in Rocket.Chat Affects Email Parameter Handling
CVE-2026-55666

9.3CRITICAL

Key Information:

Vendor

Rocketchat

Status
Rocket.chat
Vendor
CVE Published:
24 June 2026

What is CVE-2026-55666?

Rocket.Chat, a secure communications platform, has a vulnerability in its handling of Apple-issued JWTs during the OAuth authentication flow. In versions prior to 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13, the application inadequately checks for an email parameter within the JWT. Without a valid email address, the system improperly processes arbitrary email values supplied by an attacker, enabling potential account takeover. This issue is resolved in the latest updates.

Affected Version(s)

Rocket.Chat >= 8.5.0-rc.0, < 8.5.1 < 8.5.0-rc.0, 8.5.1

Rocket.Chat >= 8.4.0-rc.0, < 8.4.4 < 8.4.0-rc.0, 8.4.4

Rocket.Chat >= 8.3.0-rc.0, < 8.3.6 < 8.3.0-rc.0, 8.3.6

References

https://github.com/RocketChat/Rocket.Chat/security/adviso...
x_refsource_CONFIRM

CVSS V4

Score:
9.3
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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