CVE-2021-30479

Name: CVE-2021-30479
Creator: NVD / NIST
Published: 2021-04-15T00:15:13.17+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 0.86%

Last modified Jun 17, 2026

CVE-2021-30479 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. An issue was discovered in Zulip Server before 3.4. A bug in the implementation of the all_public_streams API feature resulted in guest users being able to receive message traffic to public streams that should have been only accessible to members of the organization.. EPSS estimates a 0.86% chance of exploitation in the next 30 days.

Description

An issue was discovered in Zulip Server before 3.4. A bug in the implementation of the all_public_streams API feature resulted in guest users being able to receive message traffic to public streams that should have been only accessible to members of the organization.

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

0.86%

53.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-269

Affected Software

Vendor	Product	Versions
Zulip	Zulip Server	< 3.4

References

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

Timeline

Published: Apr 15, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-30479?

How severe is CVE-2021-30479?

CVE-2021-30479 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.86% probability of exploitation in the next 30 days.

How do I fix CVE-2021-30479?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-30479?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST