CVE-2026-45691: Nextcloud: Bypass of second factor authentication on DAV endpoints

Medium severity · published Jun 1, 2026

CVE-2026-45691

Nextcloud: Bypass of second factor authentication on DAV endpoints

5.9

CVSS

0.3%

EPSS

On KEV

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 vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N

Attack vector

Network

Complexity

High

Privileges

Low

User interaction

None

Confidentiality

Low

Integrity

High

Availability

None

Scope

Unchanged

Exploitation

Is it being used?

Exploit prediction (EPSS)0.3% · higher than 21% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

security-advisories · nextcloud

>= 32.0.0, < 32.0.9; >= 33.0.0, < 33.0.3 · source: vendor

Nextcloud Server · Nextcloud

32.0.0 before 32.0.9; 33.0.0 before 33.0.3; 29.0.0 before 29.0.16.16; 30.0.0 before 30.0.17.9; 31.0.0 before 31.0.14.5; 32.0.0 before 32.0.9; +1 more · source: NVD

Affected product

security-advisories

nextcloud

All security-advisories CVEs

References

NVD

https://nvd.nist.gov/vuln/detail/CVE-2026-45691

CVE.org

https://www.cve.org/CVERecord?id=CVE-2026-45691

Vendor Advisory

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-mp6x-g55j-w9jw

Issue Tracking

https://github.com/nextcloud/server/pull/59758

Permissions Required

https://hackerone.com/reports/3573399