CVE-2026-20700
Apple Multiple Buffer Overflow Vulnerability
Description
CVE-2026-20700 is a high-severity memory corruption vulnerability affecting a wide range of Apple operating systems, including iOS 26.3, iPadOS 26.3, macOS Tahoe 26.3, watchOS 26.3, tvOS 26.3, and visionOS 26.3. Carrying a CVSS v3.1 base score of 7.8, this vulnerability allows an attacker who has already achieved memory write capability on a target device to execute arbitrary code by exploiting a flaw in state management. Apple has confirmed that this issue may have been actively exploited in the wild, and CISA has added it to the Known Exploited Vulnerabilities (KEV) catalog with a mandatory remediation deadline of March 5, 2026. The ransomware association is currently classified as unknown. With an EPSS score of 0.42% at the 61st percentile, the exploitation probability is moderate but elevated by the confirmed in-the-wild exploitation. The breadth of affected Apple platforms makes this vulnerability relevant to virtually the entire Apple device ecosystem, from iPhones and Macs to Apple Watches and the Vision Pro headset.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| apple | ipados | < 26.3 |
| apple | iphone os | < 26.3 |
| apple | macos | < 26.3 |
| apple | tvos | < 26.3 |
| apple | visionos | < 26.3 |
| apple | watchos | < 26.3 |
References
- https://support.apple.com/en-us/126346(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/126348(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/126351(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/126352(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/126353(Release Notes, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20700(US Government Resource)
Weakness Type
CWE-119: Buffer Overflow
CVE-2026-20700 is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). This parent weakness category encompasses vulnerabilities where software performs operations on a memory buffer without correctly verifying that the read or write operations stay within the buffer's boundaries. In the context of this Apple vulnerability, the memory corruption stems from improper state management that allows an attacker with existing memory write capability to corrupt adjacent memory regions or manipulate control flow structures. CWE-119 covers a broad class of memory safety issues including buffer overflows, out-of-bounds reads and writes, and heap corruption, all of which can lead to arbitrary code execution, denial of service, or information disclosure depending on the specific exploitation technique employed.
Impact Analysis
The impact of CVE-2026-20700 is significant across all three dimensions of the CIA triad, though the local attack vector and requirement for prior memory write capability moderate the overall risk compared to remotely exploitable vulnerabilities. Confidentiality is fully compromised upon successful exploitation, as arbitrary code execution allows the attacker to access any data stored on or accessible from the device, including personal files, photos, messages, credentials, encryption keys, and sensitive application data. On iOS and iPadOS devices, this could include health data, financial information, and private communications.
Integrity faces high impact because the attacker can modify any data or system state accessible to the executing context. This includes planting persistent backdoors, modifying system configurations, tampering with application data, and potentially escalating privileges to gain kernel-level access if the code execution occurs in a privileged context.
Availability is equally at risk, as the attacker can crash processes, corrupt system data, or render the device unusable. The CVSS vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H indicates that while the attack requires local access (AV:L) and low privileges (PR:L), it has low complexity (AC:L) and requires no user interaction (UI:N). The local access requirement means the attacker must first establish a foothold on the device, typically through a separate vulnerability in a browser, messaging application, or other network-facing service. Apple's confirmation of active exploitation suggests this vulnerability is being used as part of multi-stage exploit chains targeting specific individuals or groups.
Exploit Maturity
Apple has explicitly acknowledged that CVE-2026-20700 may have been actively exploited in the wild, which is Apple's standard phrasing for confirmed exploitation. This acknowledgment, combined with the vulnerability's inclusion in CISA's KEV catalog with a remediation deadline of March 5, 2026, confirms that threat actors have successfully weaponized this flaw. The EPSS score of 0.42% at the 61st percentile is moderate in absolute terms but should be interpreted alongside the confirmed active exploitation.
Apple zero-day vulnerabilities of this nature are typically exploited in targeted attacks, often by commercial spyware vendors or state-sponsored groups conducting surveillance operations. The requirement for existing memory write capability indicates that this vulnerability is being used as part of an exploit chain, where a separate vulnerability provides the initial memory corruption primitive and CVE-2026-20700 is leveraged to escalate from memory write to full code execution. Historical precedent with similar Apple vulnerabilities suggests involvement of sophisticated threat actors, and no public exploit code has been released, consistent with the targeted nature of the exploitation.
Remediation
-
Update all Apple devices immediately to the latest available versions: iOS 26.3, iPadOS 26.3, macOS Tahoe 26.3, watchOS 26.3, tvOS 26.3, and visionOS 26.3. Apple has published security advisories detailing the fix for each platform: iOS and iPadOS, macOS Tahoe, tvOS, watchOS, and visionOS.
-
Enable automatic updates on all Apple devices in your environment. On iOS, navigate to Settings > General > Software Update > Automatic Updates and enable all toggle options. On macOS, enable automatic updates through System Settings > General > Software Update. This ensures future security patches are applied without delay.
-
Prioritize enterprise-managed devices using MDM solutions such as Jamf, Microsoft Intune, or Mosyle. Push the required OS updates to all managed devices and set compliance policies that flag or restrict devices running vulnerable versions. Verify update deployment through MDM reporting dashboards.
-
Assess exposure for high-risk users such as executives, journalists, activists, and security personnel who are more likely targets of sophisticated exploit chains. Consider enabling Apple's Lockdown Mode on their devices, which significantly reduces the attack surface by disabling features frequently targeted by spyware.
-
Review device logs and endpoint telemetry for indicators of compromise, particularly on devices belonging to high-value targets. Look for unusual process activity, unexpected network connections, and signs of jailbreak or exploit chain artifacts. Apple's Rapid Security Response mechanism may provide additional mitigations between full OS updates.
Technical Details
CVE-2026-20700 is a memory corruption vulnerability caused by improper state management in a system component shared across multiple Apple operating systems. The CVSS v3.1 vector is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating local access with low privileges is required but exploitation is straightforward once those prerequisites are met.
The vulnerability is triggered when an attacker with existing memory write capability manipulates specific state variables that the affected component uses to manage memory operations. The improper state management means the component does not correctly track the lifecycle or validity of certain memory regions, allowing an attacker to corrupt state in a way that leads to controlled code execution. Apple addressed the issue with improved state management, suggesting the fix involves more rigorous validation of state transitions and memory region tracking.
The breadth of affected platforms is notable. iOS 26.3, iPadOS 26.3, macOS Tahoe 26.3, watchOS 26.3, tvOS 26.3, and visionOS 26.3 all contain the fix, indicating the vulnerable component is part of a shared framework or kernel subsystem used across Apple's entire operating system family. This cross-platform presence is consistent with a vulnerability in a core system library or the XNU kernel itself.
The prerequisite of memory write capability means this vulnerability is not directly exploitable from a remote context. An attacker must first achieve the ability to write to arbitrary memory locations on the target device, which typically requires a separate vulnerability such as a browser engine flaw, a messaging parser bug, or another memory corruption issue. Once memory write is established, CVE-2026-20700 provides a reliable primitive for converting that limited capability into full arbitrary code execution, making it a valuable link in exploit chains used by sophisticated attackers.
Frequently Asked Questions
What is CVE-2026-20700?
CVE-2026-20700 is a memory corruption vulnerability in Apple's operating systems that allows an attacker with existing memory write capability to execute arbitrary code. It affects iOS, iPadOS, macOS, watchOS, tvOS, and visionOS.
Is CVE-2026-20700 being actively exploited?
Yes. Apple has acknowledged that this issue may have been actively exploited, which is Apple's standard disclosure language for confirmed in-the-wild exploitation. CISA has also added it to the Known Exploited Vulnerabilities catalog.
Which Apple devices are affected by CVE-2026-20700?
All Apple devices running operating system versions prior to iOS 26.3, iPadOS 26.3, macOS Tahoe 26.3, watchOS 26.3, tvOS 26.3, and visionOS 26.3 are affected. This includes iPhones, iPads, Macs, Apple Watches, Apple TVs, and Apple Vision Pro.
Can CVE-2026-20700 be exploited remotely?
Not directly. The vulnerability requires local access and existing memory write capability, meaning an attacker must first exploit a separate vulnerability to establish a foothold on the device. However, this can be achieved through remote vectors such as malicious web pages or messages when chained with other exploits.
How do I protect my Apple devices from CVE-2026-20700?
Update all Apple devices to the latest OS versions (iOS 26.3, iPadOS 26.3, macOS Tahoe 26.3, etc.) immediately. Enable automatic updates, and consider activating Lockdown Mode on devices belonging to high-risk individuals.
Need Help With Vulnerability Management?
Our security experts can help you prioritize and remediate vulnerabilities effectively.