CVE-2026-100404Zulip: Guests can read new messages in non-subscribed public channels
Updated under an hour ago ()
Does this affect you?
It affects zulip. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
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
- 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- Weakness (CWE)
- CWE-862
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Awaiting Analysis
- Record last updated
- Oct 14, 2026
- First seen by InfoSec Signals
- Oct 14, 2026
Affected products
zulip zulip zulip:zulip (from the name) | before 12.2 | CNA record |
References
- https://github.com/zulip/zulip/security/advisories/GHSA-5r8f-gq2h-fcgpx-refsource-confirm
- https://github.com/zulip/zulip/pull/39913x-refsource-misc
- https://github.com/zulip/zulip/commit/98659a41cb93d4ce329ea14bb0cdfb4b147500bax-refsource-misc
- https://github.com/zulip/zulip/commit/c03db8916456674df3c98614f6f0ef8cd024ef11x-refsource-misc
- https://github.com/zulip/zulip/releases/tag/12.2x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.