Multiple vulnerabilities in Nextcloud Server and Enterprise Server

1) Open redirect

EUVDB-ID: #VU77659

Risk: Low

CVSSv3.1: 3.6 [CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-35171

CWE-ID: CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

Exploit availability: No

Description

The vulnerability allows a remote attacker to redirect victims to arbitrary URL.

The vulnerability exists due to improper sanitization of user-supplied data on "Unsupported browser" warning. A remote user can create a link that leads to a trusted website, however, when clicked, redirects the victim to arbitrary domain.

Successful exploitation of this vulnerability may allow a remote attacker to perform a phishing attack and steal potentially sensitive information.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 26.0.0 - 26.0.1

Nextcloud Enterprise Server: 26.0.0 - 26.0.1

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-h353-vvwv-j2r4

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Improper access control

EUVDB-ID: #VU77663

Risk: Medium

CVSSv3.1: 6.6 [CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-35927

CWE-ID: CWE-284 - Improper Access Control

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to improper access restrictions when two servers are registered as trusted servers for each other and successfully exchanged the share secrets. A remote user can modify or delete VCards in the system addressbook on the origin server.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Enterprise Server: 16.0.0 - 26.0.1

Nextcloud Server: 25.0.0 - 26.0.1

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-h7f7-535f-7q87

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

3) Improper Restriction of Excessive Authentication Attempts

EUVDB-ID: #VU77662

Risk: High

CVSSv3.1: 7.6 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-35172

CWE-ID: CWE-307 - Improper Restriction of Excessive Authentication Attempts

Exploit availability: No

Description

The vulnerability allows a remote attacker to compromise the target system.

The vulnerability exists due to missing brute force protection within the password reset endpoint. A remote attacker can brute-force the password reset links.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Enterprise Server: 21.0.0 - 26.0.1

Nextcloud Server: 25.0.0 - 26.0.1

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-mjf5-p765-qmr6

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

4) Unprotected storage of credentials

EUVDB-ID: #VU77661

Risk: Low

CVSSv3.1: 7.3 [CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-35928

CWE-ID: CWE-256 - Unprotected Storage of Credentials

Exploit availability: No

Description

The vulnerability allows a remote user to gain access to other users' credentials.

The vulnerability exists due to user scoped external storage can be used to gather credentials of other users. A remote administrator can get access to the login credentials of another user and take over their account.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Enterprise Server: 19.0.0 - 26.0.1

Nextcloud Server: 25.0.0 - 26.0.1

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-637g-xp2c-qh5h

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated privileged user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

5) Improper Restriction of Excessive Authentication Attempts

EUVDB-ID: #VU77660

Risk: High

CVSSv3.1: 7.6 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-32320

CWE-ID: CWE-307 - Improper Restriction of Excessive Authentication Attempts

Exploit availability: No

Description

The vulnerability allows a remote attacker to compromise the target system.

The vulnerability exists due to missing brute force protection. A remote user can brute-force authentication on the system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Enterprise Server: 21.0.0 - 26.0.1

Nextcloud Server: 25.0.0 - 26.0.1

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-qphh-6xh7-vffg
http://github.com/nextcloud/server/pull/38274
http://hackerone.com/reports/1918525

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.