CVE-2021-30860 vulnerability in Apple and Other Products
Published on August 24, 2021

An integer overflow was addressed with improved input validation. This issue is fixed in Security Update 2021-005 Catalina, iOS 14.8 and iPadOS 14.8, macOS Big Sur 11.6, watchOS 7.6.2. Processing a maliciously crafted PDF may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.

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Known Exploited Vulnerability

This Apple iOS "FORCEDENTRY" Remote Code Execution Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. An integer overflow was addressed with improved input validation vulnerability affecting iOS devices that allows for remote code execution.

The following remediation steps are recommended / required by November 17, 2021: Apply updates per vendor instructions.

Vulnerability Analysis

CVE-2021-30860 is exploitable with local system access, requires user interaction. This vulnerability is considered to have a low attack complexity. It has an exploitability score of 1.8 out of four. The potential impact of an exploit of this vulnerability is considered to be very high.

Integer Overflow or Wraparound

The software performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. An integer overflow or wraparound occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may wrap to become a very small or negative number. While this may be intended behavior in circumstances that rely on wrapping, it can have security consequences if the wrap is unexpected. This is especially the case if the integer overflow can be triggered using user-supplied inputs. This becomes security-critical when the result is used to control looping, make a security decision, or determine the offset or size in behaviors such as memory allocation, copying, concatenation, etc.