CVE-2025-31478: zulip server Auth Bypass (CVSS 8.2)

Description

Zulip is an open-source team collaboration tool. Zulip supports a configuration where account creation is limited solely by being able to authenticate with a single-sign on authentication backend, meaning the organization places no restrictions on email address domains or invitations being required to join, but has disabled the EmailAuthBackend that is used for email/password authentication. A bug in the Zulip server means that it is possible to create an account in such organizations, without having an account with the configured SSO authentication backend. This issue is patched in version 10.2. A workaround includes requiring invitations to join the organization prevents the vulnerability from being accessed.

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CVSS v3.1 Score

8.2

HIGH

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

Weakness Type (CWE)

CWE-287 Improper Authentication

Affected Products

Vendor	Product	Versions
zulip	zulip_server	< 10.2

References

Other References

https://github.com/zulip/zulip/commit/b5ab90aaa4a7efdcbf886cb9e7d55fa5bfca3a28 https://github.com/zulip/zulip/security/advisories/GHSA-qxfv-j6vg-5rqc

Frequently Asked Questions

What is CVE-2025-31478? +

Zulip is an open-source team collaboration tool. Zulip supports a configuration where account creation is limited solely by being able to authenticate with a single-sign on authentication backend, meaning the organization places no restrictions on email address domains or invitations being required to join, but has disabled the EmailAuthBackend that is used for email/password authentication. A bug in the Zulip server means that it is possible to create an account in such organizations, without having an account with the configured SSO authentication backend. This issue is patched in version 10.2. A workaround includes requiring invitations to join the organization prevents the vulnerability from being accessed. It has a CVSS v3.1 base score of 8.2 (HIGH).

How severe is CVE-2025-31478? +

CVE-2025-31478 has a CVSS v3.1 score of 8.2 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-31478? +

CVE-2025-31478 affects products from zulip, specifically: zulip_server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-31478? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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