CVE-2021-1871

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

As of , CVE-2021-1871 in Apple iOS, iPadOS, and macOS is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch soon.

Exploited
Yes: CISA listed it on 3 November 2021
US federal deadline
17 November 202114 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.07Higher than 93% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
EPSS when listed
Not availableCISA listed it before 4 February 2022, where the EPSS files we read begin.
Public exploit
None foundNeither Metasploit nor Exploit-DB lists one.
Fix
No vendor link in CISA's entry

What CISA says to do

Apply updates per vendor instructions.

CISA's required action

What the flaw is

Apple iOS, iPadOS, and macOS WebKit contain an unspecified logic vulnerability that allows a remote attacker to execute code. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

CISA's description

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..

The CVE record's description, from apple

CVE published
2 April 2021
Assigned by
apple
CVSS
9.8 Critical (CVSS 3.1, from CISA-ADP)
CWE-1173
Improper Use of Validation Framework
CISA SSVC, exploitation
active
CISA SSVC, automatable
yes
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.

iOS, iPadOS, and macOS: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2020-9934Input ValidationApple iOS, iPadOS, and macOSPatch this weekMetasploit module0.03
CVE-2023-41064ImageIO Buffer OverflowApple iOS, iPadOS, and macOSPatch this weekEPSS 0.530.53
CVE-2025-43300Out-of-Bounds WriteApple iOS, iPadOS, and macOSPatch soon0.32
CVE-2023-28206IOSurfaceAccelerator Out-of-Bounds WriteApple iOS, iPadOS, and macOSPatch soon0.23
CVE-2022-22620Webkit Use-After-FreeApple iOS, iPadOS, and macOSPatch soon0.16
CVE-2021-30858iOS, iPadOS, macOS Use-After-FreeApple iOS, iPadOS, and macOSPatch soon0.13
CVE-2021-1870WebKit Remote Code ExecutionApple iOS, iPadOS, and macOSPatch soon0.08
CVE-2021-30900Out-of-Bounds WriteApple iOS, iPadOS, and macOSPatch soon0.05
CVE-2022-32917Remote Code ExecutionApple iOS, iPadOS, and macOSPatch soon0.06
CVE-2021-30869Type ConfusionApple iOS, iPadOS, and macOSPatch soon0.04

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