CVE-2026-45264: CWE-284: Improper Access Control in nextcloud security-advisories
Nextcloud is an open source content collaboration platform. From versions 17.0.0 to before 17.0.15, 18.0.0 to before 18.1.12, 19.0.0 to before 19.1.16, 20.0.0 to before 20.1.11, and 21.0.0 to before 21.0.4, a user with READ and CREATE permission, but no UPDATE permission for a team folder can rename files in the team folder. This issue has been patched in versions 17.0.15, 18.1.12, 19.1.16, 20.1.11, and 21.0.4.
AI Analysis
Technical Summary
CVE-2026-45264 is an improper access control vulnerability (CWE-284) in Nextcloud's team folder permissions. Specifically, users granted READ and CREATE permissions but not UPDATE permission could rename files in team folders, which should not be allowed. This issue affects multiple Nextcloud versions from 17.0.0 through 21.0.0 prior to their respective patch versions. The vulnerability has been fixed in subsequent releases starting with 17.0.15, 18.1.12, 19.1.16, 20.1.11, and 21.0.4.
Potential Impact
The vulnerability allows users with limited permissions (READ and CREATE but no UPDATE) to rename files in team folders, potentially leading to unauthorized modification of file metadata or organization. There is no impact on confidentiality or availability reported. The CVSS score of 4.3 (medium severity) reflects the limited scope of impact, primarily an integrity concern without elevation of privileges beyond the user's existing access level.
Mitigation Recommendations
A fix is available and has been released in Nextcloud versions 17.0.15, 18.1.12, 19.1.16, 20.1.11, and 21.0.4. Users and administrators should upgrade affected Nextcloud instances to these or later versions to remediate the vulnerability. No additional mitigation steps are indicated by the vendor advisory.
CVE-2026-45264: CWE-284: Improper Access Control in nextcloud security-advisories
Description
Nextcloud is an open source content collaboration platform. From versions 17.0.0 to before 17.0.15, 18.0.0 to before 18.1.12, 19.0.0 to before 19.1.16, 20.0.0 to before 20.1.11, and 21.0.0 to before 21.0.4, a user with READ and CREATE permission, but no UPDATE permission for a team folder can rename files in the team folder. This issue has been patched in versions 17.0.15, 18.1.12, 19.1.16, 20.1.11, and 21.0.4.
CVSS v3.1
Score 4.3medium
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-45264 is an improper access control vulnerability (CWE-284) in Nextcloud's team folder permissions. Specifically, users granted READ and CREATE permissions but not UPDATE permission could rename files in team folders, which should not be allowed. This issue affects multiple Nextcloud versions from 17.0.0 through 21.0.0 prior to their respective patch versions. The vulnerability has been fixed in subsequent releases starting with 17.0.15, 18.1.12, 19.1.16, 20.1.11, and 21.0.4.
Potential Impact
The vulnerability allows users with limited permissions (READ and CREATE but no UPDATE) to rename files in team folders, potentially leading to unauthorized modification of file metadata or organization. There is no impact on confidentiality or availability reported. The CVSS score of 4.3 (medium severity) reflects the limited scope of impact, primarily an integrity concern without elevation of privileges beyond the user's existing access level.
Mitigation Recommendations
A fix is available and has been released in Nextcloud versions 17.0.15, 18.1.12, 19.1.16, 20.1.11, and 21.0.4. Users and administrators should upgrade affected Nextcloud instances to these or later versions to remediate the vulnerability. No additional mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-11T18:41:13.156Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a1dbba7e29bf47b501c5805
Added to database: 6/1/2026, 5:04:39 PM
Last enriched: 6/1/2026, 5:20:15 PM
Last updated: 6/2/2026, 4:58:44 AM
Views: 4
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