Vulnerability identifier: #VU32903

Vulnerability risk: Low

CVSSv3.1: 3.8 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-15658

CWE-ID: CWE-20

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 bypass certain security restrictions.

The vulnerability exists due to insufficient validation of special characters during file download, which led to an attacker being able to cut off the file ending at an earlier position, leading to a different file type being downloaded than shown in the dialog. A remote attacker can override file type when saving data to disk.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 70.0 - 78.0.2

Firefox ESR: 78.0 - 78.0.2

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2020-30/
http://www.mozilla.org/en-US/security/advisories/mfsa2020-32/

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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.