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PatchSiren cyber security CVE debrief

CVE-2021-1871 Apple CVE debrief

CVE-2021-1871 is a CISA Known Exploited Vulnerabilities (KEV) entry for Apple iOS, iPadOS, and macOS. The issue is identified as a WebKit remote code execution vulnerability, which makes it a high-priority patch item for Apple device fleets. CISA added it to KEV on 2021-11-03 and set a remediation due date of 2021-11-17, so organizations should treat it as actively important and verify updates were applied per Apple guidance.

Vendor
Apple
Product
iOS, iPadOS, and macOS
CVSS
Unknown
CISA KEV
Listed
Original CVE published
2021-11-03
Original CVE updated
2021-11-03
Advisory published
2021-11-03
Advisory updated
2021-11-03

Who should care

Apple device administrators, endpoint security teams, mobile device management (MDM) operators, and users of iPhone, iPad, and Mac systems that rely on WebKit-based browsing or embedded web content.

Technical summary

The supplied record identifies CVE-2021-1871 as a WebKit remote code execution vulnerability affecting Apple iOS, iPadOS, and macOS. The CISA KEV listing indicates the vulnerability is known to be exploited in the wild or otherwise confirmed as a current exploitation concern, and CISA directs organizations to apply updates per vendor instructions.

Defensive priority

Critical. This is a KEV-listed Apple vulnerability with a short remediation window, so patching and exposure verification should be treated as immediate.

Recommended defensive actions

  • Apply Apple security updates for the affected platforms as soon as possible.
  • Verify fleet-wide remediation on iOS, iPadOS, and macOS devices, including managed and unmanaged endpoints where possible.
  • Prioritize internet-facing, high-risk, and user-facing devices that regularly process untrusted web content.
  • Use MDM or endpoint management reporting to confirm the relevant Apple updates are installed.
  • Monitor Apple security advisories and CISA KEV updates for any follow-on guidance or related issues.

Evidence notes

The classification and urgency are based on the supplied CISA KEV source item, which names the issue as an Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability and lists it as a KEV entry with required action: apply updates per vendor instructions. The only official links provided are the CVE record, NVD detail page, CISA KEV catalog, and the source item URL. No CVSS score was supplied in the corpus.

Official resources

Publicly listed in the CISA Known Exploited Vulnerabilities catalog on 2021-11-03, with a remediation due date of 2021-11-17.