CVE-2026-3336

High

Published: 02 March 2026

Published

02 March 2026

Modified

11 March 2026

KEV Added

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Patch

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CVSS Score 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS Score 0.0001 3.0th percentile

Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-3336 is a high-severity Improper Certificate Validation (CWE-295) vulnerability in Amazon Aws-Lc-Sys. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 3.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique.

Threat & Defense Details

Likely Mitigating ControlsAI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SA-19 Component Authenticity

addresses: CWE-295

When certificates are used to establish component provenance, the control requires correct certificate validation procedures.

SC-17 Public Key Infrastructure Certificates

addresses: CWE-295

Mandates approved trust anchors and issuance policies, directly preventing acceptance of unvalidated or untrusted certificates.

SC-45 System Time Synchronization

addresses: CWE-295

Correct system time is required for proper enforcement of certificate notBefore/notAfter dates and time-based revocation checks.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1553.002 Code Signing Defense Impairment

Adversaries may create, acquire, or steal code signing materials to sign their malware or tools.

attack.mitre.org →

Why these techniques?

Remote unauthenticated network exploitation of apps using the vulnerable library for PKCS7 signature verification directly matches T1190; the core flaw bypasses certificate chain validation to accept invalid signatures, enabling subversion of code/data signing trust controls per T1553.002.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v18.1

NVD Description

Improper certificate validation in PKCS7_verify() in AWS-LC allows an unauthenticated user to bypass certificate chain verification when processing PKCS7 objects with multiple signers, except the final signer. Customers of AWS services do not need to take action. Applications using AWS-LC…

should upgrade to AWS-LC version 1.69.0.

Deeper analysisAI

CVE-2026-3336 is an improper certificate validation vulnerability in the PKCS7_verify() function of the AWS-LC library. It enables bypassing certificate chain verification when processing PKCS7 objects that include multiple signers, excluding the final signer. The flaw, classified under CWE-295, carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N) and affects applications directly using AWS-LC.

An unauthenticated attacker can exploit this vulnerability remotely over the network with low attack complexity, requiring no privileges or user interaction. Exploitation allows the attacker to bypass certificate chain checks on PKCS7 objects with multiple signers (except the final one), resulting in high integrity impact by enabling acceptance of invalid signatures.

AWS security bulletin 2026-005-AWS, along with the GitHub security advisory GHSA-cfwj-9wp5-wqvp and release notes for AWS-LC v1.69.0, recommend upgrading affected applications to AWS-LC version 1.69.0 to mitigate the issue. Customers of AWS services do not need to take any action.