CVE-2021-1871VulnerabilityPublished 11/03/2021Updated 10/24/2026

CVE-2021-1871: Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability

Affects Apple iOS, iPadOS, and macOSSource CISA KEV

Severity

High

No CVSS score published yet

Exploitation: Actively exploited – in CISA KEV since 11/03/2021
KEV deadline: 11/17/2021
EPSS: 7.0% chance of exploitation in 30 days – higher than 94% of CVEs

What to do

CISA required action

Apply updates per vendor instructions.

nvd.nist.gov/vuln/detail/CVE-2021-1871 (opens in a new tab)

Description

CVE-2021-1871 is a high-severity remote code execution vulnerability in Apple iOS, iPadOS, and macOS WebKit. It involves an unspecified logic flaw that allows remote attackers to execute arbitrary code via HTML parsing. This affects Apple Safari and other products using WebKit for HTML processing. Exploits have been observed in the wild. No specific affected versions or patch status are provided.

Summary

Apple's WebKit component in iOS, iPadOS, and macOS contains an unspecified logic vulnerability (CWE-1173) that enables remote code execution. This flaw impacts HTML parsers relying on WebKit, including Apple Safari and potentially non-Apple products using WebKit. The vulnerability has been exploited in the wild, indicating active threat. No detailed technical specifics or patch information are provided in the available data.

Impact

Successful exploitation allows remote attackers to execute arbitrary code on affected devices running iOS, iPadOS, or macOS. This can lead to full system compromise or unauthorized actions within the context of the vulnerable WebKit component. The presence of known exploits in the wild increases the urgency of addressing this vulnerability.

Mitigation

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until official fixes are confirmed and applied, users should exercise caution when browsing untrusted web content or opening links. Monitor Apple security updates for patches addressing this vulnerability.

Weaknesses

CWE-1173Unclassified weakness (opens in a new tab)

What to do

Description

AnalysisAI-generated, updated 10/24/2026, 09:41:08 UTC

Weaknesses

References

Related threats