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CVE Record

CVE-2026-3338: PKCS7_verify Signature Validation Bypass in AWS-LC

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 1.69.0.

HighCVSS 8.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-3338 lets a malformed PKCS7 object bypass signature checks in AWS-LC when Authenticated Attributes are processed. This can undermine trust decisions in applications that rely on AWS-LC for PKCS7 verification. AWS says customers of AWS services do not need action; applications using AWS-LC should upgrade.

Executive priority

Treat as a high-priority integrity issue for software that directly embeds AWS-LC. It does not appear to require AWS service customer action, and no active exploitation evidence is provided, but affected verification workflows should be upgraded promptly.

Technical view

The issue is CWE-347 improper signature validation in AWS-LC PKCS7_verify(). It is network-reachable, unauthenticated, low-complexity, and requires no user interaction per CVSS 4.0 score 8.7. The bundle identifies AWS-LC 1.41.0 and directs application users to AWS-LC 1.69.0.

Likely exposure

Exposure is most likely in applications or products directly using AWS-LC to verify PKCS7 objects, especially externally supplied PKCS7 data with Authenticated Attributes. The provided AWS bulletin says AWS service customers do not need to take action. Evidence for other affected products is not provided.

Exploitation context

The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The risk is integrity failure: a relying application may accept data as signed or valid when PKCS7 signature verification should fail.

Researcher notes

Analysis is limited to the provided bundle. The bundle names the vulnerable function, weakness class, CVSS vector, upgrade target, and Red Hat references, but does not provide exploit status, detailed affected version ranges beyond AWS-LC 1.41.0, or compensating controls.

Mitigation direction

  • Upgrade applications using AWS-LC to AWS-LC version 1.69.0.
  • Apply Red Hat errata if consuming AWS-LC through affected Red Hat packages.
  • Review AWS and GitHub advisories for updated vendor scope.
  • Prioritize systems that verify externally supplied PKCS7 data.
  • If upgrade timing is blocked, follow vendor guidance for temporary risk handling.

Validation and detection

  • Inventory applications and packages that include AWS-LC.
  • Confirm whether AWS-LC 1.41.0 is present in deployed builds.
  • Identify code paths using PKCS7_verify() on untrusted PKCS7 objects.
  • Check whether PKCS7 Authenticated Attributes are accepted in relevant workflows.
  • Verify upgraded builds report AWS-LC version 1.69.0 or vendor-fixed packages.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-347: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-3338 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.7 (4.0)
Known Exploited
No
Published

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

3CVSS vectors
5Timeline events
2ADP providers
8Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

3 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.7CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N——AMZN
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6AMZN
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

8.7High
CVSS 4.0 vector shape for CVE-2026-3338Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPaws-lc: AWS-LC: Signature bypass due to improper validation in PKCS7_verify()
other:Red Hat severity ratingcvssV3_1
  • 2026-03-02T22:01:12.080Z: Reported to Red Hat.
  • 2026-03-02T21:22:41.954Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
AWSAWS-LC1.41.0unaffected
Weakness

CWE details

CWE-347

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-347 · source CWE mapping

Improper Verification of Cryptographic Signature

Improper Verification of Cryptographic Signature represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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