CVE-2026-93578
Published:September 18, 2026
Updated:October 09, 2026
A flaw was found in Netty's Online Certificate Status Protocol (OCSP) Client. The client fails to verify the 'id-kp-OCSPSigning' Extended Key Usage (EKU) in OCSP responder certificates. A remote attacker, holding any valid certificate issued by the same Certificate Authority (CA), can exploit this by forging 'GOOD' OCSP responses for revoked certificates. This bypasses certificate revocation checks, allowing applications using Netty's OCSP Client to accept certificates that should have been revoked, leading to an authorization bypass.
Affected Packages
https://github.com/netty/netty.git (GITHUB):
Affected version(s) >=netty-4.2.0.Final <netty-4.2.18.FinalFix Suggestion:
Update to version netty-4.2.18.Finalhttps://github.com/netty/netty.git (GITHUB):
Affected version(s) >=netty-4.1.86.Final <netty-4.1.138.FinalFix Suggestion:
Update to version netty-4.1.138.Finalio.netty:netty-handler-ssl-ocsp (JAVA):
Affected version(s) >=4.2.0.Final <4.2.18.FinalFix Suggestion:
Update to version 4.2.18.Finalio.netty:netty-handler-ssl-ocsp (JAVA):
Affected version(s) >=4.1.86.Final <4.1.138.FinalFix Suggestion:
Update to version 4.1.138.FinalRelated Resources (3)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.2
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.9
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
EPSS
Base Score:
0.23