CVE-2026-3338
Published: 02 March 2026
Summary
CVE-2026-3338 is a high-severity Improper Verification of Cryptographic Signature (CWE-347) vulnerability in Amazon Aws-Lc-Sys. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Code Signing (T1553.002); 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
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.
Requires verification of digital signatures using organization-approved certificates before installation, directly preventing improper verification of cryptographic signatures.
Component authenticity commonly depends on cryptographic signatures; the control enforces proper verification of those signatures.
PKI certificates under an approved policy require cryptographic signature verification on issuance and validation.
Requires cryptographic signatures on authoritative data and support for verifying the chain of trust.
Mandates verification of cryptographic signatures (e.g., DNSSEC RRSIG) on resolution responses, addressing missing or bypassed signature checks.
Integrity tools commonly rely on cryptographic signatures whose improper validation this weakness covers.
Authenticity validation commonly relies on cryptographic signature or certificate checks that this control enforces.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The vulnerability directly enables bypassing cryptographic signature verification for PKCS7/CMS objects (commonly used for code signing), which maps to subverting code signing trust controls.
NVD Description
Improper signature validation in PKCS7_verify() in AWS-LC allows an unauthenticated user to bypass signature verification when processing PKCS7 objects with Authenticated Attributes. Customers of AWS services do not need to take action. Applications using AWS-LC should upgrade to AWS-LC version…
more
1.69.0.
Deeper analysisAI
CVE-2026-3338 is an improper signature validation vulnerability (CWE-347) in the PKCS7_verify() function of the AWS-LC cryptographic library. Published on 2026-03-02, it enables bypassing signature verification when processing PKCS7 objects that include Authenticated Attributes. The vulnerability affects applications using vulnerable versions of AWS-LC, with 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).
An unauthenticated attacker can exploit this flaw remotely with low attack complexity and no user interaction or privileges required. By crafting malicious PKCS7 objects with Authenticated Attributes, the attacker bypasses signature checks, achieving high integrity impact without affecting confidentiality or availability.
AWS security advisories state that customers of AWS services require no action, as the issue is addressed in managed services. Applications using AWS-LC directly must upgrade to version 1.69.0 for mitigation. Details are provided in the AWS security bulletin (https://aws.amazon.com/security/security-bulletins/2026-005-AWS/), AWS-LC release notes (https://github.com/aws/aws-lc/releases/tag/v1.69.0), and GitHub advisory (https://github.com/aws/aws-lc/security/advisories/GHSA-jchq-39cv-q4wj).
Details
- CWE(s)