Auth bypass in Zulip
CVE-2026-25741
Zulip is an open-source team collaboration tool. Prior to commit bf28c82dc9b1f630fa8e9106358771b20a0040f7, the API endpoint for creating a card update session during an upgrade flow was accessible to users with only organization member privileges. When the associated Stripe Checkout session is completed, the Stripe webhook updates the organization’s default payment method. Because no billing-specific authorization check is enforced, a regular (non-billing) member can change the organization’s payment method. This vulnerability affected the Zulip Cloud payment processing system, and has been patched as of commit bf28c82dc9b1f630fa8e9106358771b20a0040f7. Self-hosted deploys are no longer affected and no patch or upgrade is required for them.
Vulnerability class: Broken Access Control
EPSS: 0.003 (19.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L.
Affected products
- Zulip — versions < bf28c82dc9b1f630fa8e9106358771b20a0040f7
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-25741?
- CVE-2026-25741 is a high-severity vulnerability in Zulip, classified under Incorrect Authorization. CVSS score: 7.1/10. Published 2026-02-26.
- How severe is CVE-2026-25741?
- High severity. CVSS v3 base score is 7.1 out of 10.