Auth bypass in Fossasia Open-Event-Server
CVE-2026-63101
Open Event Server through 1.19.1 contains a missing authentication vulnerability that allows unauthenticated attackers to export the complete member roster of any group, including email addresses, names, join dates, and roles, by submitting requests to the group followers CSV export endpoint which lacks any authentication decorator. Attackers can enumerate sequential group IDs via brute-force, trigger an export via the unauthenticated POST endpoint, then poll the unauthenticated task status endpoint until completion to retrieve a download URL containing the full member CSV.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.005 (43.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 43.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Fossasia Open-Event-Server — versions 0
Weakness classification (CWE)
References
- github.com/geo-chen/oss/blob/main/open-event-server.md (technical-description, exploit)
- www.vulncheck.com/advisories/open-event-server-unauthenticated-member-roster-ex… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-63101?
- CVE-2026-63101 is a high-severity vulnerability in Fossasia Open-Event-Server, classified under Missing Authentication for Critical Function. CVSS score: 7.5/10. Published 2026-07-17.
- How severe is CVE-2026-63101?
- High severity. CVSS v3 base score is 7.5 out of 10.