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CVE-2021-30666 High

Confirmed as exploited

CVE-2021-30666

A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 12.5.3. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

Exploit probability 3.0%
Published September 8, 2021
Required by November 17, 2021
Last source change March 14, 2026

01 / ACTION

Required action

Apply updates per vendor instructions.

02 / AFFECTED SOFTWARE

Affected packages

Unknown Unknown

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Cybersecurity and Infrastructure Security Agency Known Exploited Vulnerabilities CVE-2021-30666

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.

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Open Source Vulnerabilities CVE-2021-30666

A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 12.5.3. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

View original source

05 / REFERENCES

Further evidence