Vulnerability identifier: #VU53652

Vulnerability risk: Medium

CVSSv3.1: 5.1 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-33511

CWE-ID: CWE-918

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Plone
Web applications / CMS

Vendor: Plone

Description

The disclosed vulnerability allows a remote attacker to perform SSRF attacks.

The vulnerability exists due to insufficient validation of user-supplied input in the lxml parser. A remote attacker can send a specially crafted HTTP request and trick the application to initiate requests to arbitrary systems.

Successful exploitation of this vulnerability may allow a remote attacker gain access to sensitive data, located in the local network or send malicious requests to other servers from the vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Plone: 5.0 rc1 - 5.2.4

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External links
http://plone.org/security/hotfix/20210518/server-side-request-forgery-via-lxml-parser
http://www.openwall.com/lists/oss-security/2021/05/22/1

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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.