Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HSummary
CVE-2026-20639 is a high-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Apple Macos. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 46th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-20639 is an integer overflow vulnerability (CWE-190) that was addressed through improved input validation in various macOS versions. It affects macOS Sequoia prior to 15.7.5, macOS Sonoma prior to 14.8.5, and macOS Tahoe prior to 26.3. The flaw occurs during the processing of a maliciously crafted string, which can trigger heap corruption.
The vulnerability has a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), indicating it is exploitable over a network with low attack complexity, requiring no privileges or user interaction. Remote attackers can send a specially crafted string to affected systems, leading to heap corruption and potential denial-of-service through application crashes or system instability, though no direct confidentiality or integrity impacts are noted.
Apple's security advisories detail the fixes in the specified macOS updates (https://support.apple.com/en-us/126348, https://support.apple.com/en-us/126795, https://support.apple.com/en-us/126796). Security practitioners should prioritize patching to macOS Sequoia 15.7.5, Sonoma 14.8.5, or Tahoe 26.3, as these releases incorporate the input validation improvements to prevent exploitation.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-15043
Vulnerability Data
An integer overflow was addressed with improved input validation. This issue is fixed in macOS Sequoia 15.7.5, macOS Sonoma 14.8.5, macOS Tahoe 26.3. Processing a maliciously crafted string may lead to heap corruption.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.2.6
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (static analysis, fuzzing, unit tests) directly finds integer overflow defects before deployment.
Secure engineering principles require use of safe arithmetic constructs or language features that structurally eliminate integer overflow during calculation.
Input validation enforces bounds on values before arithmetic, stopping the conditions that trigger overflow or wraparound.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require use of safe arithmetic, bounds checks, and testing that prevent integer overflows.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development can detect integer overflows before release.
Secure SDLC mandates input validation and arithmetic checks that prevent integer overflows.
Application security requirements include bounds checking and safe arithmetic to avoid overflow conditions.
Secure architecture principles require defensive coding patterns that mitigate integer wraparound risks.
Secure coding standards explicitly forbid unsafe integer operations and mandate overflow-safe constructs.