Vulnerability Report

CVE-2026-45691

Title: 2FA Bypass via pre-2FA session cookie in Nextcloud Server

Auth Bypass

Proof Of Concept

No public PoC currently indexed for CVE-2026-45691.

CWE Category CWE-287
Published Date Jun 01, 2026
Modified Date Jul 22, 2026
Exploit Status Not Found
Score 5.9 CVSS v3.1
Exploit Probability (EPSS)
0.43%

Vulnerability Summary

CVE-2026-45691: 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

Impacted Vendors

N
nextcloud 1

Reference Links

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-mp6x-g55j-w9jw https://github.com/nextcloud/server/pull/59758 https://hackerone.com/reports/3573399
CVSS v3.1
Source Entity [email protected]
Severity MEDIUM
5.9
Attack Vector
NETWORK
Complexity
HIGH
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-45691 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity HIGH
Privileges N/A
Interaction NONE
CVSS Vector String CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N

Affected Stack

No specific products linked.