#VU107580 Improper Authentication in Zulip Server - CVE-2025-31478

Vulnerability identifier: #VU107580

Vulnerability risk: High

CVSSv4.0: 6.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2025-31478

CWE-ID: CWE-287

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Zulip Server
Web applications / Other software

Vendor: Zulip

Description

The vulnerability allows a remote attacker to bypass authentication process.

The vulnerability exists due to authentication backend configuration bypass. A remote attacker can create an account without having an account with the configured SSO authentication backend.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Zulip Server: 10.0 - 10.1

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External links
https://github.com/zulip/zulip/security/advisories/GHSA-qxfv-j6vg-5rqc

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.