CVE-2021-30858 Apple iOS, iPadOS, and macOS: memory-safety flaw

In plain words: The program mishandles the memory it uses to keep track of data. A specially made input can scramble that memory. Usually lets an attacker crash the program or run their own code with its permissions.

Confirmed exploited by CISA on Nov 3, 2021 · US federal patch deadline Nov 17, 2021

What to do

Install Apple's security update for iOS, iPadOS, and macOS. If no update exists, follow the vendor's workaround or stop using the product until one ships.
Install system updates the day they come out — most phone zero-days are fixed in a point release.
Restart your phone every few days; some spyware does not survive a reboot.
If you are a journalist, activist, lawyer, politician or executive, turn on Lockdown Mode (iPhone) or Advanced Protection (Android).

Who is affected

Could reach you. This one is aimed at devices or apps of the kind people own.

What's at risk: Messages, photos, location, microphone and camera. The most serious ones are "zero-click": no tap needed from the owner. They are usually used as spyware against a small number of chosen people.

The details

Official name: Apple iOS, iPadOS, macOS Use-After-Free Vulnerability
Product: Apple iOS, iPadOS, and macOS
CISA description: Apple iOS, iPadOS, and macOS WebKit contain a use-after-free 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.
Type of flaw: Memory-safety flaw (CWE-416)
Confirmed exploited: Nov 3, 2021
US federal patch deadline: Nov 17, 2021

NVD record ↗CISA catalog ↗

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Answering about CVE-2021-30858 ·

Questions about CVE-2021-30858

Is CVE-2021-30858 being exploited?

Yes. CISA added CVE-2021-30858 to its Known Exploited Vulnerabilities catalog on Nov 3, 2021, which means there is reliable evidence of real-world attacks.

How do I fix CVE-2021-30858?

Install Apple's security update for iOS, iPadOS, and macOS. If no update exists, follow the vendor's workaround or stop using the product until one ships. Install system updates the day they come out — most phone zero-days are fixed in a point release.

Am I affected by CVE-2021-30858?

Only if you use Apple iOS, iPadOS, and macOS. This one is aimed at devices or apps of the kind people own.