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 3.1
- 6.5
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - EPSS
- 0.4% chance of exploitation in the next 30 days; higher than 35% of CVEs (scores of 2026-10-25)
- CWE
- CWE-862
- Published
- Modified
- Record from
- the NVD, synced
References
- 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