Apple Multiple Products Classic Buffer Overflow
CVE-2025-43520 is a medium-severity buffer copy without checking size of input vulnerability in iOS and iPadOS from Apple, with a CVSS 3.1 base score of 5.5 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 18.7.2, 26.1 as the first without the flaw, so updating iOS and iPadOS to one of those releases or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on March 20, 2026, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update iOS and iPadOS to 18.7.2 or 26.1, whichever matches your release line, or a later version.
- Update macOS to 14.8.2 or 15.7.2 or 26.1, whichever matches your release line, or a later version.
- Update tvOS to 26.1 or a later version.
- CISA's required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- Read the advisory on support.apple.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Apple | iOS and iPadOS | before 18.7.2; before 26.1 | 18.7.2, 26.1 |
| Apple | macOS | before 14.8.2; before 15.7.2; before 26.1 | 14.8.2, 15.7.2, 26.1 |
| Apple | tvOS | before 26.1 | 26.1 |
| Apple | visionOS | before 26.1 | 26.1 |
| Apple | watchOS | before 26.1 | 26.1 |
| Apple | iPadOS | before 18.7.2; 26.0 | 18.7.2 |
| Apple | Iphone OS | before 18.7.2; 26.0 | 18.7.2 |
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
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 5.5 | Medium | NVD |
| CVSS 3.1 | 5.5 | Medium | CISA (ADP) |
Official description
A memory corruption issue was addressed with improved memory handling. This issue is fixed in iOS 18.7.2 and iPadOS 18.7.2, iOS 26.1 and iPadOS 26.1, macOS Sequoia 15.7.2, macOS Sonoma 14.8.2, macOS Tahoe 26.1, tvOS 26.1, visionOS 26.1, watchOS 26.1. A malicious application may be able to cause unexpected system termination or write kernel memory.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Buffer Copy without Checking Size of Input
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
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 Buffer Copy without Checking Size of Input vulnerabilities (CWE-120)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Deadline for US federal agencies to remediate, set by CISA.
- Record last changed materially (score, affected products, status or references).
References
Advisories
- support.apple.com/en-us/125632Release Notes
- support.apple.com/en-us/125633Release Notes
- support.apple.com/en-us/125634Release Notes
- support.apple.com/en-us/125635Release Notes
- support.apple.com/en-us/125636Release Notes
- support.apple.com/en-us/125637Release Notes
- support.apple.com/en-us/125638Release Notes
- support.apple.com/en-us/125639Release Notes
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-43520US Government Resource
Other references
- cloud.google.com/blog/topics/threat-intelligence/darksword-ios-exploit-chain/Technical Description
Other vulnerabilities in iOS and iPadOS
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Recent Buffer Copy without Checking Size of Input vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.0 High severity
- 9.8 Critical severity
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