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🛡️ CVE-2026-4428 — aws-lc-fips-sys

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-295 NVD
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

CRL Distribution Point Scope Check Logic Error in AWS-LC

Summary

AWS-LC is an open-source, general-purpose cryptographic library.

Impact

A logic error in CRL distribution point matching in AWS-LC allows a revoked certificate to bypass revocation checks during certificate validation, when the application enables CRL checking and uses partitioned CRLs with Issuing Distribution Point (IDP) extensions.

Customers of AWS services do not need to take action. aws-lc-sys and aws-lc-fips-sys contain code from AWS-LC. Applications using aws-lc-sys or aws-lc-fips-sys should upgrade to the most recent releases of aws-lc-sys or aws-lc-fips-sys.

Impacted versions:

  • aws-lc-sys >= v0.15.0, < v0.39.0
  • aws-lc-fips-sys >= v0.13.0, < v0.13.13

Patches

The patch is included in aws-lc-sys v0.39.0 and aws-lc-fips-sys v0.13.13.

Workarounds

Applications can workaround this issue if they do not enable CRL checking (X509_V_FLAG_CRL_CHECK). Applications using complete (non-partitioned) CRLs without IDP extensions are also not affected.

Otherwise, there is no workaround and applications using aws-lc-sys or aws-lc-fips-sys should upgrade to the most recent releases of aws-lc-sys or aws-lc-fips-sys.

References

If you have any questions or comments about this advisory, we ask that you contact AWS Security via our [vulnerability reporting page](https://aws.amazon.com/security/vulnerability-reporting/) or directly via email to [[email protected]](mailto:[email protected]). Please do not create a public GitHub issue.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: None.

Weakness class

CVE-2026-4428 is classified as CWE-295: Improper Certificate Validation. A TLS certificate is accepted without proper verification, so a man-in-the-middle can present their own.

Affected software

CVE-2026-4428 is recorded against 3 packages.

  • aws-lc-fips-sys
  • aws-lc-sys
  • unknown

Timeline and source

Published on 19 March 2026 and last revised on 24 March 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

crates.io (Package)
rustsec.org (Advisory)
aws.amazon.com (Web)
github.com (Advisory)

Other advisories for this package

aws-lc-fips-sys has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-295: Improper Certificate Validation) in other software:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE CWE-295
Public Exploit ✅ No
Source NVD
Published 2026-03-19
Updated 2026-08-20
Modified 2026-03-24
Fix URL N/A

Affected Packages

Software From version Fixed in
aws-lc-fips-sys — —
aws-lc-sys — —
unknown — —

Similar Threats

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