Multiple vulnerabilities in Nextcloud Server



Published: 2021-01-25
Risk Medium
Patch available YES
Number of vulnerabilities 2
CVE-ID CVE-2020-8293
CVE-2020-8294
CWE-ID CWE-399
CWE-79
Exploitation vector Network
Public exploit N/A
Vulnerable software
Subscribe 		Nextcloud Server
Client/Desktop applications / Messaging software

Vendor Nextcloud

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Resource management error

EUVDB-ID: #VU49974

Risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-8293

CWE-ID: CWE-399 - Resource Management Errors

Exploit availability: No

Description

The vulnerability allows a remote user to perform a denial of service (DoS) attack.

The vulnerability exists due to improper management of internal resources within the application when storing data in workflow rules. A remote user can store a huge amount of data and perform a denial of service (DoS) attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 18.0.0 - 20.0.1

External links

http://nextcloud.com/security/advisory/?id=NC-SA-2021-001
http://hackerone.com/reports/1018146


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) Stored cross-site scripting

EUVDB-ID: #VU49975

Risk: Low

CVSSv3.1: 4.7 [CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-8294

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 user to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data in markdown file with Nextcloud Talk. A remote user can store 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: 18.0.0 - 20.0.1

External links

http://nextcloud.com/security/advisory/?id=NC-SA-2021-002
http://hackerone.com/reports/1023787


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.



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