Medium severity · published Jun 1, 2026
CVE-2026-45543
Nextcloud: Deleting a Forms collaborator share leaves uploaded response files accessible through a lingering Files share
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 19% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SE
security-advisories · nextcloud
>= 4.3.0, < 5.2.7 · source: vendor
FO
Forms · Nextcloud
4.3.0 before 5.2.7 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-45543
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-45543
Issue Tracking
https://github.com/nextcloud/forms/pull/3291
Mitigation
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-q4fw-6jf8-5vhh
Permissions Required
https://hackerone.com/reports/3617352
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