Vulnerability identifier: #VU24060

Vulnerability risk: Medium

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-2019-17022

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Mozilla Firefox
Client/Desktop applications / Web browsers
Firefox ESR
Client/Desktop applications / Web browsers

Vendor: Mozilla

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 within the CSS sanitizer. When pasting a tag from the clipboard into a rich text editor, the CSS sanitizer does not escape < and > characters. If a webpage subsequently copies the node's innerHTML, assigning it to another innerHTML, this would result in an XSS vulnerability.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 65.0 - 71.0

Firefox ESR: 68.0 - 68.3.0, 60.0 - 60.9.0

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2020-01/

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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.