CVE-2026-56820
Received
Received - Intake
OCSP Response Replay in Netty Framework
Vulnerability report for CVE-2026-56820, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-07-21
Last updated on: 2026-07-21
Assigner: GitHub, Inc.
Description
Description
Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and prior to 4.1.135.Final, `OcspClient` does not validate that the `CertificateID` in an OCSP response matches the requested `CertificateID`, which can lead to replay attack. `OcspClient.validateResponse` accepts a legitimately signed `GOOD` status response for an unrelated certificate issued by the same CA, allowing bypass of revocation checks for another certificate. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| netty | netty | From 4.2.0.Final (inc) to 4.2.15.Final (inc) |
| netty | netty | to 4.1.135.Final (exc) |
| netty | netty | 4.1.136.Final |
| netty | netty | 4.2.16.Final |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-295 | The product does not validate, or incorrectly validates, a certificate. |
