Vulnerability identifier: #VU50021

Vulnerability risk: Medium

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

CVE-ID: CVE-2021-23953

CWE-ID: CWE-200

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

The vulnerability exists due to cross-origin information leak when processing PDF files. A remote attacker can create a specially crafted PDF file, trick the victim into opening it and gain access to sensitive information via redirected PDF requests, when said information is served as chunked data.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 60.0 - 84.0.2

Firefox ESR: 78.0 - 78.6.1, 68.0 - 68.12.0, 60.0 - 60.9.0

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2021-03/
http://www.mozilla.org/en-US/security/advisories/mfsa2021-04/

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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.