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PatchSiren cyber security CVE debrief

CVE-2021-30761 Apple CVE debrief

CVE-2021-30761 is an Apple iOS WebKit memory corruption vulnerability that CISA included in its Known Exploited Vulnerabilities (KEV) catalog. For defenders, the key takeaway is not the internal bug detail but the exposure signal: CISA marked it as a known exploited issue and set a remediation due date of 2021-11-17. Follow Apple’s update guidance and prioritize deployment on iOS devices that may still be running vulnerable software.

Vendor
Apple
Product
iOS
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

Organizations that manage Apple iOS devices, including mobile device management teams, endpoint security teams, and IT administrators responsible for prompt OS patching. Individual users should also care if they have not recently updated their iPhone or iPad.

Technical summary

The supplied records identify the issue as a WebKit memory corruption vulnerability affecting Apple iOS. The available corpus does not provide affected version ranges, attack vector specifics, or exploit mechanics. What is confirmed is that CISA categorized it as a known exploited vulnerability and referenced Apple’s update path rather than a custom mitigation.

Defensive priority

High. CISA placed the issue in KEV, which is a strong indicator that remediation should be expedited. The catalog entry also includes a short due date window, reinforcing the need for prompt patching.

Recommended defensive actions

  • Apply Apple updates per vendor instructions as soon as possible.
  • Verify which iOS devices are still on unsupported or delayed update paths.
  • Use mobile device management or asset inventory to confirm patch status across the fleet.
  • Treat the KEV due date of 2021-11-17 as the remediation target in internal tracking.
  • Monitor for any residual vulnerable WebKit-based components on managed Apple devices.

Evidence notes

CVE and vendor context come from the official CVE record and NVD detail page. The exploitation priority comes from CISA’s Known Exploited Vulnerabilities catalog entry, which lists Apple, iOS, dateAdded 2021-11-03, dueDate 2021-11-17, and the required action: apply updates per vendor instructions. No CVSS score or affected-version detail was provided in the supplied corpus.

Official resources

CISA KEV entry dated 2021-11-03 identifies CVE-2021-30761 as a known exploited vulnerability and recommends applying updates per vendor instructions.