CVE-2021-30477 json
An issue was discovered in Zulip Server before 3.4.
published 2021-04-14 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-17400
- cvss
- 4.3
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 51%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- zulip zulip_server 3.4
Exploit prediction
0.66% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 4.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N |
| NVD | 2.0 | 4.0 | AV:N/AC:L/Au:S/C:N/I:P/A:N |
References
-
blog.zulip.com
/2021/04/14/zulip-server-3-4/
release-notes, vendor-advisory
Sources
- CVE List CVE-2021-30477
- NVD CVE-2021-30477
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.