Raw vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:NSummary
CVE-2026-27221 is a medium-severity Improper Certificate Validation (CWE-295) vulnerability in Apple Macos. Its CVSS base score is 5.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Code Signing (T1553.002); ranked at the 1th 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 IA-5 (Authenticator Management) and SC-17 (Public Key Infrastructure Certificates) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-10901
Vulnerability Data
Acrobat Reader versions 24.001.30307, 24.001.30308, 25.001.21265 and earlier are affected by an Improper Certificate Validation vulnerability that could result in a Security feature bypass. An attacker could leverage this vulnerability to spoof the identity of a signer. Exploitation of this…
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- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Improper certificate validation (CWE-295) directly enables spoofing signer identity, mapping to subversion of code/document signing trust controls.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
- 12 hardening rules · 3 OS baselines
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Mitigating Controls (NIST 800-53 r5) AI
Directly requires verification of certificate holder identity and proper authenticator validation, blocking spoofed signer certificates.
Mandates issuance and use of PKI certificates under approved policies that enforce correct validation chains.
Requires integrity verification of signed content, which depends on trustworthy certificate validation to detect spoofing.
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.
Certificate-based authentication of users/services/hardware directly depends on correct validation.
Proper certificate validation is a core mechanism for protecting data-in-transit confidentiality and integrity.
Secure development practices explicitly include implementing correct certificate validation logic.
Assessing authenticity/integrity of acquired software often relies on code-signing certificate validation.
Identity assertions conveyed via certificates require validation to be verified.
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.
Requiring issuance and validation of public-key certificates under an approved policy reduces the chance that certificates with improper validation will be trusted.
Hardening callouts derived
Configuration rules from DISA STIG baselines that reduce the attack surface for weaknesses of the type cited by this CVE. Derived transitively via CVE→CWE→STIG over `controls_xwalks` (authoritative rows only).
Oracle Linux 8 (2 rules)
- V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. via CWE-295
- V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. via CWE-295
RHEL 7 (1 rule)
- V-204447 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. via CWE-295
RHEL 8 (2 rules)
- V-230264 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. via CWE-295
- V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. via CWE-295