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PatchSiren cyber security CVE debrief

CVE-2021-1870 Apple CVE debrief

CVE-2021-1870 is an Apple WebKit remote code execution vulnerability affecting iOS, iPadOS, and macOS. CISA added it to the Known Exploited Vulnerabilities catalog on 2021-11-03 and set a remediation due date of 2021-11-17, so this should be treated as a patch-now issue for exposed Apple fleets.

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

IT and security teams responsible for Apple iPhone, iPad, and Mac fleets; endpoint management teams; and anyone operating systems that rely on Apple platform updates.

Technical summary

The supplied corpus identifies this as a WebKit remote code execution issue in Apple iOS, iPadOS, and macOS. Because it is listed in CISA’s KEV catalog, defenders should assume it was known to be exploited and prioritize vendor updates over routine maintenance windows. No additional root cause, exploit chain, or affected-version detail is present in the supplied source item.

Defensive priority

High. KEV inclusion and the short remediation window indicate urgent patching and verification are warranted.

Recommended defensive actions

  • Apply Apple updates per vendor instructions as soon as feasible.
  • Inventory iOS, iPadOS, and macOS assets to confirm exposure and update coverage.
  • Prioritize internet-facing, high-risk, and user-browsing devices first.
  • Verify remediation before the KEV due date and track any exceptions separately.
  • Monitor security advisories and endpoint telemetry for signs of suspicious activity while patching is in progress.

Evidence notes

Source item metadata from CISA KEV labels the issue as "Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability," marks it as a known exploited vulnerability, and gives a required action of "Apply updates per vendor instructions." The corpus provides the CVE and KEV dates (2021-11-03) and the remediation due date (2021-11-17), but does not include a vendor advisory, CVSS score, affected build numbers, or exploit details.

Sources and references

Verified primary and authoritative sources

  • CVE-2021-1870 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2021-1870

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2021-1870 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2021-1870

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

    cisa_kev

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.