Exploited vulnerability · CISA KEV

Is CVE-2021-30666 exploited? Yes: in CISA KEV since 3 Nov 2021

Gociux · Apple iOS · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2021-30666, Apple iOS WebKit Buffer Overflow Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 3 Nov 2021, 56 days after it was published. It affects Apple iOS. If you run it, CISA's required action is: Apply updates per vendor instructions.

exploitedYesCISA KEV · 3 Nov 2021

ransomwareNot knownno confirmed use

EPSSbelow top 10%lower predicted activity right now (it is still confirmed exploited)

severity8.8CVSS 3.1 · high

US federal due17 Nov 2021BOD 22-01 deadline

What it is

Apple iOS WebKit contains a buffer-overflow vulnerability that leads to code execution when processing maliciously crafted web content. 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.

Vendor	Apple (96 exploited CVEs in KEV)
Product	iOS
Vulnerability	Apple iOS WebKit Buffer Overflow Vulnerability
Weakness	CWE-119
Published	8 Sep 2021
Added to KEV	3 Nov 2021
Reported by (CNA)	apple

What to do

Check whether you run it. Look for iOS in your asset inventory, including appliances and cloud images. Stack check lists every exploited Apple CVE at once.
Apply the fix. Apply updates per vendor instructions.
If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 8 Sep 2021.
Get told next time. Email alerts when CISA adds a CVE for Apple.

Other exploited CVEs in iOS

CVE-2022-42856: Apple iOS Type Confusion Vulnerability (14 Dec 2022)
CVE-2016-4655: Apple iOS Information Disclosure Vulnerability (24 May 2022)
CVE-2016-4656: Apple iOS Memory Corruption Vulnerability (24 May 2022)
CVE-2016-4657: Apple iOS Webkit Memory Corruption Vulnerability (24 May 2022)
CVE-2019-7287: Apple iOS Memory Corruption Vulnerability (23 May 2022)
CVE-2021-30762: Apple iOS WebKit Use-After-Free Vulnerability (3 Nov 2021)

References

nvd.nist.gov/vuln/detail/CVE-2021-30666

Questions

Is CVE-2021-30666 being exploited?

Yes. CISA added CVE-2021-30666 to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, which means there is reliable evidence of exploitation in the wild.

Is CVE-2021-30666 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2021-30666?

Apply updates per vendor instructions. Check Apple's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected iOS and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in November 2021 · Apple scorecard · act-now radar.

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