CyberSecBulletin
CVE-2023-40423NVD status: Modified

iOS and iPadOS: Improper Restriction of Operations within the Bounds of a Memory Buffer

Published Updated By the CyberSecBulletin desk

CVE-2023-40423 is a high-severity improper restriction of operations within the bounds of a memory buffer vulnerability in iOS and iPadOS from Apple, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists versions 16.7, 17.1 as the first without the flaw, so updating iOS and iPadOS to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.42% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update iOS and iPadOS to 16.7 or 17.1, whichever matches your release line, or a later version.
  2. Update macOS to 14.1 or 13.6 or 12.7, whichever matches your release line, or a later version.
  3. Update iPadOS to 16.7.2 or 17.1, whichever matches your release line, or a later version.
  4. Read the advisory on support.apple.com for workarounds and exact fixed builds.
  5. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
AppleiOS and iPadOSbefore 16.7; before 17.116.7, 17.1
ApplemacOSbefore 14.1; before 13.6; before 12.714.1, 13.6, 12.7
AppleiPadOSbefore 16.7.2; 17.0 up to, but not including, 17.116.7.2, 17.1
AppleIphone OSbefore 16.7.2; 17.0 up to, but not including, 17.116.7.2, 17.1

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by NVD.

Official description

The issue was addressed with improved memory handling. This issue is fixed in iOS 17.1 and iPadOS 17.1, macOS Monterey 12.7.1, iOS 16.7.2 and iPadOS 16.7.2, macOS Ventura 13.6.1, macOS Sonoma 14.1. An app may be able to execute arbitrary code with kernel privileges.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerabilities (CWE-119)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in iOS and iPadOS

All iOS and iPadOS vulnerabilities

Recent Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerabilities

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