CVE-2026-100404

Zulip is an open-source team collaboration tool. In Zulip Server versions through 12.1, guest users can receive new message events for public channels outside their subscriptions. A guest can trigger the issue by registering an event queue with parameters that request messages from an unsubscribed public channel, or an existing event queue can remain affected after the guest's access to the channel is removed. The flaw discloses new public-channel messages to the guest. This issue is fixed in version 12.2.

CVSS v3 6.5 MEDIUM

6.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/zulip/zulip/commit/98659a41cb93d4ce329ea14bb0cdfb4b147500ba
https://github.com/zulip/zulip/commit/c03db8916456674df3c98614f6f0ef8cd024ef11
https://github.com/zulip/zulip/pull/39913
https://github.com/zulip/zulip/releases/tag/12.2
https://github.com/zulip/zulip/security/advisories/GHSA-5r8f-gq2h-fcgp

Configurations

No configuration.

History

14 Oct 2026, 16:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-14 16:17

Updated : 2026-10-29 15:17

NVD link : CVE-2026-100404

Mitre link : CVE-2026-100404

CVE.ORG link : CVE-2026-100404

JSON object : View

Products Affected

No product.

CWE

CWE-862

Missing Authorization

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