#VU52609 Out-of-bounds write in macOS - CVE-2021-1881

Vulnerability identifier: #VU52609

Vulnerability risk: High

CVSSv4.0: 6.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2021-1881

CWE-ID: CWE-787

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
macOS
Operating systems & Components / Operating system

Vendor: Apple Inc.

Description

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a boundary error when processing font files within the GetFDIndex function in libFontParser. A remote attacker can create a specially crafted OTF font, trick the victim into a document of a web page with the malicious font, trigger out-of-bounds write and execute arbitrary code on the target system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

macOS: 10.14 18A391 - 10.15.7 19H524, 11.0 20A2411 - 11.2.3 20D91

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External links
https://support.apple.com/en-us/HT212326
https://support.apple.com/en-us/HT212325
https://support.apple.com/en-us/HT212327
https://www.zerodayinitiative.com/advisories/ZDI-21-600/

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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.