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CVE-2026-63101 fossasia CVE debrief

CVE-2026-63101 is a high-severity vulnerability in Open Event Server through version 1.19.1. The vulnerability allows unauthenticated attackers to export the complete member roster of any group, including sensitive information such as email addresses, names, join dates, and roles. This is achieved by exploiting the unauthenticated POST endpoint for CSV export of group followers, which lacks proper authentication. The vulnerability exists due to a missing authentication decorator in the group followers CSV export endpoint. Attackers can enumerate sequential group IDs via brute-force, trigger an export via the unauthenticated POST endpoint, and then poll the unauthenticated task status endpoint until completion to retrieve a download URL containing the full member CSV.

Vendor
fossasia
Product
open-event-server
CVSS
HIGH 8.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-17
Original CVE updated
2026-07-17
Advisory published
2026-07-17
Advisory updated
2026-07-17

Who should care

Administrators and security teams responsible for Open Event Server installations should prioritize patching this vulnerability to prevent potential data breaches. They should review the official advisory and CVE record to validate affected scope, severity, and vendor guidance. Security teams should also monitor for suspicious activity related to group follower exports and conduct regular security audits and vulnerability assessments.

Technical summary

The vulnerability exists in the group followers CSV export endpoint of Open Event Server. This endpoint lacks authentication, allowing attackers to export member rosters by submitting requests with sequential group IDs. The process involves brute-forcing group IDs, triggering an export via the unauthenticated POST endpoint, and polling the task status endpoint to retrieve a download URL containing the full member CSV. The vulnerability allows unauthenticated attackers to access sensitive information, including email addresses, names, join dates, and roles of group members.

Defensive priority

High

Recommended defensive actions

  • Apply patches or updates to Open Event Server to version 1.19.2 or later.
  • Implement authentication and authorization for the CSV export endpoint.
  • Monitor for suspicious activity related to group follower exports.
  • Conduct regular security audits and vulnerability assessments.
  • Restrict access to sensitive endpoints and implement rate limiting.
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
  • Review compensating controls for exposed systems while remediation is scheduled and verified.

Evidence notes

The CVE record was published on 2026-07-17T17:17:17.283Z and has not been modified since then. The NVD entry is currently Deferred. There is limited information available about the vulnerability from the source item. Further verification is needed to confirm affected scope and severity. Defenders should review the official CVE record and NVD details for CVE-2026-63101.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-17T17:17:17.283Z and has not been modified since then.