CVE-2026-3336Network attack vector

Certificate-chain bypass via final-signer-only validation

Published Mar 2, 2026 · Updated Mar 2, 2026

Improper certificate validation in AWS-LC 1.41.0 through 1.68.0 allows remote attackers to bypass PKCS7 signer-chain checks. PKCS7_verify initializes a certificate context for each signer, but X509_verify_cert executes only after the signer loop, so only the final chain is checked. With no privileges or user interaction required, a crafted multi-signer object can introduce unverified earlier chains and subvert integrity decisions.

CVSS severity8.7
High
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in AWS-LC 1.41.0 through 1.68.0 allows remote attackers to bypass PKCS7 signer-chain checks. PKCS7_verify initializes a certificate context for each signer, but X509_verify_cert executes only after the signer loop, so only the final chain is checked. With no privileges or user interaction required, a crafted multi-signer object can introduce unverified earlier chains and subvert integrity decisions.

The record

CVE
CVE-2026-3336
Published
Mar 2, 2026
Updated
Mar 2, 2026
Vendor
Amazon Web Services
Product
AWS-LC
Classifications
CWE-295, T1553
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.41.0 <1.69.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Amazon Web Services · AWS-LCversion=1.41.0 <1.69.0

Published CVSS scores

7.5AMZNCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
7.5redhat-SADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
8.7AMZNCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1553Subvert Trust Controls

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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