CVE-2021-30477

4.3 mediumEPSS 0.7%

Medium (4.3) in zulip zulip server. EPSS 0.7% chance of exploitation in the next 30 days.

An issue was discovered in Zulip Server before 3.4. A bug in the implementation of replies to messages sent by outgoing webhooks to private streams meant that an outgoing webhook bot could be used to send messages to private streams that the user was not intended to be able to send messages to.

Severity

CVSS 3.1

4.3 medium

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

EPSS: 0.7% chance of exploitation in the next 30 days; higher than 51% of CVEs (scores of 2026-10-31)
Published: 2021-04-15
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

zulip:zulip_server

References

https://blog.zulip.com/2021/04/14/zulip-server-3-4/
https://blog.zulip.com/2021/04/14/zulip-server-3-4/

Check your stack JSON