CVE-2026-100404
The flaw discloses new public-channel messages to the guest.
Does this matter?
Lower severity and a low EPSS score (0.41%). Track it; it rarely justifies an emergency change on its own.
Description
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 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- EPSS
- 0.41% probability · 36th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-862
- Source
- security-advisories@github.com
EPSS moved from 0.4% on 15 October 2026 to 0.4% on 26 October 2026.
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.