Cyber Threat Intelligence
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CRITICAL · CVSS 9.8 CISA Known Exploited Vulnerability

CVE-2021-1870

Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability

Apple iOS, iPadOS, and macOS

A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

CVSS
9.8
CRITICAL
EPSS
7.7%
30-day exploitation
Ransomware groups
0
recorded exploiting
Published
2 Apr 2021
NVD

Exploitation status

CISA Known Exploited Vulnerabilities

Listed by CISA on 3 November 2021. US federal agencies were required to remediate it by 17 November 2021.

EPSS — exploitation probability

FIRST puts the probability of exploitation activity in the next 30 days at 7.7%, which is higher than 94.5% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Frequently asked questions

Is CVE-2021-1870 being exploited by ransomware groups?

No ransomware group in this database is currently recorded as exploiting CVE-2021-1870.

What does CVE-2021-1870 affect?

CVE-2021-1870 affects Apple iOS, iPadOS, and macOS. A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

How severe is CVE-2021-1870?

CVE-2021-1870 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 7.7%, higher than 94.5% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 17 November 2021.

How should organisations respond to CVE-2021-1870?

Apply the vendor patch for Apple iOS, iPadOS, and macOS as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.