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
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Nextcloud Server
Client/Desktop applications / Messaging software

Vendor Nextcloud

Security Advisory

1) Resource management error

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] [PCI]

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, 18.0.1, 18.0.2, 18.0.3, 18.0.4, 18.0.5, 18.0.6, 18.0.7, 18.0.8, 18.0.9, 18.0.10, 19.0.0, 19.0.1, 19.0.2, 19.0.3, 19.0.4, 20.0.0, 20.0.1

CPE External links

https://nextcloud.com/security/advisory/?id=NC-SA-2021-001
https://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

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] [PCI]

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, 18.0.1, 18.0.2, 18.0.3, 18.0.4, 18.0.5, 18.0.6, 18.0.7, 18.0.8, 18.0.9, 18.0.10, 19.0.0, 19.0.1, 19.0.2, 19.0.3, 19.0.4, 20.0.0, 20.0.1

CPE External links

https://nextcloud.com/security/advisory/?id=NC-SA-2021-002
https://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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