Multiple vulnerabilities in Nextcloud Server

1) Cross-site scripting

EUVDB-ID: #VU54665

Risk: Low

CVSSv3.1: 5.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-32733

CWE-ID: CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Exploit availability: No

Description

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data in the Text application. A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in user's browser in context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 19.0.0 - 21.0.2

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-x4w3-jhcr-57pq/

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.

2) Improper control of interaction frequency

EUVDB-ID: #VU54673

Risk: Medium

CVSSv3.1: 4.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-32703

CWE-ID: CWE-799 - Improper Control of Interaction Frequency

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to sensitive information on the target system.

The vulnerability exists due to a lack of ratelimiting on the shareinfo endpoint. A remote attacker can enumerate potentially valid share tokens.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 19.0.0 - 21.0.2

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-375p-cxxq-gc9p/

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.

3) Permissions, Privileges, and Access Controls

EUVDB-ID: #VU54671

Risk: Medium

CVSSv3.1: 6.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-32725

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: No

Description

The vulnerability allows a remote attacker to escalate privileges on the system.

The vulnerability exists due to default share permissions are not respected for federated reshares of files and folders, which leads to security restrictions bypass and privilege escalation.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 19.0.0 - 21.0.2

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-6f6v-h9x9-jj4v/

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) Information disclosure

EUVDB-ID: #VU54670

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-32734

CWE-ID: CWE-200 - Information exposure

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to the Nextcloud Text application shipped with Nextcloud server did return verbatim exception messages to the user. A remote attacker can gain unauthorized access to sensitive information on the system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 19.0.0 - 21.0.2

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-6hf5-c2c4-2526/

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.

5) Incorrect Ownership Assignment

EUVDB-ID: #VU54669

Risk: Medium

CVSSv3.1: 6.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-32726

CWE-ID: CWE-708 - Incorrect Ownership Assignment

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to sensitive information on the target system.

The vulnerability exists due to the Webauthn tokens are not deleted after a user has been deleted. If a victim reuse an earlier used username, the previous user can gain access to their account.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 19.0.0 - 21.0.2

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-6qr9-c846-j8mg/

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.

6) Improper control of interaction frequency

EUVDB-ID: #VU54668

Risk: Medium

CVSSv3.1: 4.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-32741

CWE-ID: CWE-799 - Improper Control of Interaction Frequency

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to sensitive information on the target system.

The vulnerability exists due to a lack of ratelimiting on the public share link mount endpoint. A remote attacker can enumerate potentially valid share tokens.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 19.0.0 - 21.0.2

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-crvj-vmf7-xrvr/

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.

7) Improper control of interaction frequency

EUVDB-ID: #VU54667

Risk: Medium

CVSSv3.1: 4.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-32705

CWE-ID: CWE-799 - Improper Control of Interaction Frequency

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to sensitive information on the target system.

The vulnerability exists due to a lack of ratelimiting on the public DAV endpoint. A remote attacker can enumerate potentially valid share tokens or credentials.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 19.0.0 - 21.0.2

External links

http://github.com/nextcloud/security-advisories/security/advisories/GHSA-fjv7-283f-5m54/

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.