Vulnerability in Nextcloud Forms
CVE-2026-45543
Nextcloud is an open source content collaboration platform. From version 4.3.0 to before version 5.2.7, a removed collaborator retains unauthorized read access to uploaded respondent files for the affected form. The scope is limited to uploaded files for forms where that user previously had results access. This issue has been patched in version 5.2.7.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.005 (37.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
- Nextcloud Forms
- Nextcloud Security-Advisories — versions >= 4.3.0, < 5.2.7
Weakness classification (CWE)
References
- github.com/nextcloud/security-advisories/security/advisories/GHSA-q4fw-6jf8-5vhh (Mitigation, Vendor Advisory)
- github.com/nextcloud/forms/pull/3291 (Patch, Issue Tracking)
- hackerone.com/reports/3617352 (Permissions Required)
Frequently asked questions
- What is CVE-2026-45543?
- CVE-2026-45543 is a medium-severity vulnerability in Nextcloud Forms, classified under Files or Directories Accessible to External Parties. CVSS score: 5.3/10. Published 2026-06-01.
- How severe is CVE-2026-45543?
- Medium severity. CVSS v3 base score is 5.3 out of 10.