RUSTSEC-2026-0046: PKCS7_verify Certificate Chain Validation Bypass in AWS-LC

What to do

1. See which version you have: cargo tree -i aws-lc-sys (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p aws-lc-sys. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example aws-lc-sys = "0.38.0") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

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. aws-lc-sys contains code from AWS-LC. Applications using aws-lc-sys should upgrade to the most recent release of aws-lc-sys.

There is no workaround; applications using aws-lc-sys should upgrade to the most recent release of aws-lc-sys.

References

• Package: crates.io/crates/aws-lc-sys
• Advisory: rustsec.org/advisories/RUSTSEC-2026-0046.html
• Web: aws.amazon.com/security/security-bulletins/2026-005-AWS
• Advisory: github.com/aws/aws-lc-rs/security/advisories/GHSA-vw5v-4f2q-w9xf

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.

Other advisories for aws-lc-sys

• VulnerabilityRUSTSEC-2026-0044 · 2026-03-19AWS-LC X.509 Name Constraints Bypass via Wildcard/Unicode CN
• Vulnerability MediumRUSTSEC-2026-0045 · 2026-03-02Timing Side-Channel in AES-CCM Tag Verification in AWS-LC
• Vulnerability HighRUSTSEC-2026-0047 · 2026-03-02PKCS7_verify Signature Validation Bypass in AWS-LC
• Vulnerability HighRUSTSEC-2026-0048 · 2026-03-19CRL Distribution Point Scope Check Logic Error in AWS-LC

Full security history of aws-lc-sys