CVE-2026-4428
Raw vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XSummary
CVE-2026-4428 is a critical-severity Improper Check for Certificate Revocation (CWE-299) vulnerability in Amazon (inferred from references). Its CVSS base score is 9.1 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Subvert Trust Controls (T1553); ranked at the 17th 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) — 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-2026-4428 is a logic error in the Certificate Revocation List (CRL) distribution point validation process in AWS-LC versions prior to 1.71.0. This flaw causes partitioned CRLs to be incorrectly rejected as out of scope, allowing revoked certificates to bypass certificate revocation checks. The vulnerability carries a CVSS v3.1 base score of 7.4 (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N) and maps to CWE-299 (Improper Check for Certificate Revocation).
Remote attackers without privileges or user interaction can exploit this issue, though it requires high attack complexity. Exploitation enables the use of revoked certificates to evade revocation validation, potentially leading to high-impact confidentiality and integrity violations, such as unauthorized data access or interception in TLS connections relying on affected AWS-LC implementations.
The AWS security bulletin (2026-010-AWS) and AWS-LC release notes recommend upgrading to AWS-LC 1.71.0 or AWS-LC-FIPS-3.3.0 to remediate the vulnerability by correcting the CRL validation logic.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-13237
Vulnerability Data
A logic error in CRL distribution point validation in AWS-LC before 1.71.0 causes partitioned CRLs to be incorrectly rejected as out of scope, which allows a revoked certificate to bypass certificate revocation checks. To remediate this issue, users should upgrade…
more
to AWS-LC 1.71.0 or AWS-LC-FIPS-3.3.0.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V12.1.4
Mitigating Controls (NIST 800-53 r5) AI
Authenticator management requires verification and lifecycle handling of certificates, which structurally prevents use of revoked ones when revocation status is part of the process.
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 requires valid, non-revoked certificates; proper revocation checking is a core implementation detail of this control.
Protecting data-in-transit commonly relies on TLS certificate validation that includes revocation status checks.
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.
Mandates use of cryptography including certificate validation and revocation checking.
Security testing can detect missing or incorrect certificate revocation checks.
Secure coding practices should include proper certificate revocation verification.
Requires secure authentication mechanisms that rely on valid certificates.
Network security controls can enforce certificate validation at network boundaries.
Security of network services includes certificate-based authentication and revocation checks.