OAuth2 Authorization Flaw in traQ Messenger Application by traPtitech
CVE-2026-63198

7.3HIGH

Key Information:

Vendor

Traptitech

Status
Traq
Vendor
CVE Published:
3 November 2026

What is CVE-2026-63198?

The traQ messenger application by traPtitech has a vulnerability allowing attackers to exploit silent OAuth2 authorization requests. This occurs when the prompt parameter is set to 'none' and the scope parameter is either empty or omitted. Under these circumstances, an attacker controlling an OAuth client can obtain broader access tokens than originally consented to by a user. Users who have only authorized specific client scopes may inadvertently allow access to additional scopes without additional consent, posing a significant risk to user privacy and security. The issue has been addressed in version 3.28.3.

Affected Version(s)

traQ < 3.28.3

References

https://github.com/traPtitech/traQ/security/advisories/GH...
x_refsource_CONFIRM
https://github.com/traPtitech/traQ/commit/5510fe8aa9bb15f...
x_refsource_MISC
https://github.com/traPtitech/traQ/releases/tag/v3.28.3
x_refsource_MISC

CVSS V3.1

Score:
7.3
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.