Netty prior 4.1.136.Final/4.2.16.Final certificate validation

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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3.6$0-$5k2.67

Summaryinfo

A vulnerability was found in Netty. It has been declared as problematic. This affects an unknown function. Executing a manipulation can lead to certificate validation. This vulnerability is registered as CVE-2026-56821. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability classified as problematic was found in Netty. This vulnerability affects some unknown processing. The manipulation with an unknown input leads to a certificate validation vulnerability. The CWE definition for the vulnerability is CWE-295. The product does not validate, or incorrectly validates, a certificate. As an impact it is known to affect integrity. CVE summarizes:

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response to bypass revocation of a since-revoked certificate. Exploitation can lead to certificate revocation bypass via replay of an expired OCSP response. Any application using OcspServerCertificateValidator is affected; a revoked certificate can be accepted. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-56821 since 06/23/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1587.003.

Upgrading to version 4.1.136.Final or 4.2.16.Final eliminates this vulnerability.

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Productinfo

Name

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.7
VulDB Meta Temp Score: 3.6

VulDB Base Score: 3.7
VulDB Temp Score: 3.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Certificate validation
CWE: CWE-295 / CWE-287
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Netty 4.1.136.Final/4.2.16.Final

Timelineinfo

06/23/2026 CVE reserved
07/28/2026 +35 days VulDB entry created
07/29/2026 +0 days Advisory disclosed
07/29/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-56821 (🔒)
GCVE (CVE): GCVE-0-2026-56821
GCVE (VulDB): GCVE-100-384040

Entryinfo

Created: 07/29/2026 01:39
Changes: 07/29/2026 01:39 (52)
Complete: 🔍
Cache ID: 216::103

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