CVE-2026-45691: CWE-287: Improper Authentication in nextcloud security-advisories
Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, a pre-2FA session cookie (created after successful password authentication but before TOTP completion) could be reused as a Bearer token to authenticate against DAV endpoints, granting read/write access and bypassing mandatory two-factor authentication. It is recommended that the Nextcloud Server is upgraded to 33.0.3 or 32.0.9. It is recommended that the Nextcloud Enterprise Server is upgraded to 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9 or 29.0.16.16
AI Analysis
Technical Summary
CVE-2026-45691 is an improper authentication vulnerability (CWE-287) in Nextcloud Server affecting versions 32.0.0 to before 32.0.9 and 33.0.0 to before 33.0.3. The flaw allows reuse of a pre-2FA session cookie, created after password authentication but before completing TOTP, as a Bearer token to authenticate against DAV endpoints. This results in bypassing mandatory two-factor authentication and grants read/write access to the affected resources. The vulnerability has a CVSS 3.1 base score of 5.9, indicating medium severity. The vendor recommends upgrading to fixed versions 33.0.3 or 32.0.9 for the community server, and specified patched versions for the Enterprise Server.
Potential Impact
An attacker who obtains a pre-2FA session cookie can reuse it to bypass two-factor authentication and gain read/write access to DAV endpoints on the Nextcloud Server. This compromises the integrity and confidentiality of data accessible via these endpoints. The vulnerability does not affect availability. There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrade Nextcloud Server to version 33.0.3 or 32.0.9 or later. For Nextcloud Enterprise Server, upgrade to versions 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, or 29.0.16.16 as applicable. Patch status is confirmed by vendor recommendations. No alternative mitigations are indicated.
CVE-2026-45691: CWE-287: Improper Authentication in nextcloud security-advisories
Description
Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, a pre-2FA session cookie (created after successful password authentication but before TOTP completion) could be reused as a Bearer token to authenticate against DAV endpoints, granting read/write access and bypassing mandatory two-factor authentication. It is recommended that the Nextcloud Server is upgraded to 33.0.3 or 32.0.9. It is recommended that the Nextcloud Enterprise Server is upgraded to 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9 or 29.0.16.16
CVSS v3.1
Score 5.9medium
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-45691 is an improper authentication vulnerability (CWE-287) in Nextcloud Server affecting versions 32.0.0 to before 32.0.9 and 33.0.0 to before 33.0.3. The flaw allows reuse of a pre-2FA session cookie, created after password authentication but before completing TOTP, as a Bearer token to authenticate against DAV endpoints. This results in bypassing mandatory two-factor authentication and grants read/write access to the affected resources. The vulnerability has a CVSS 3.1 base score of 5.9, indicating medium severity. The vendor recommends upgrading to fixed versions 33.0.3 or 32.0.9 for the community server, and specified patched versions for the Enterprise Server.
Potential Impact
An attacker who obtains a pre-2FA session cookie can reuse it to bypass two-factor authentication and gain read/write access to DAV endpoints on the Nextcloud Server. This compromises the integrity and confidentiality of data accessible via these endpoints. The vulnerability does not affect availability. There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrade Nextcloud Server to version 33.0.3 or 32.0.9 or later. For Nextcloud Enterprise Server, upgrade to versions 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, or 29.0.16.16 as applicable. Patch status is confirmed by vendor recommendations. No alternative mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-13T04:38:01.164Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a1de30be29bf47b503a5708
Added to database: 6/1/2026, 7:52:43 PM
Last enriched: 6/1/2026, 7:55:11 PM
Last updated: 6/2/2026, 5:05:42 AM
Views: 5
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