MAVEN · JULY 2026 · EARLY WARNING

Netty's OcspClient Vulnerability: Potential Replay Attacks

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.
GHSA-272M-GCWP-MPWGSeverity: HIGH

An early warning has been issued regarding a potential vulnerability in Netty's OcspClient, which reportedly fails to validate the CertificateID in OCSP responses, potentially enabling replay attacks.

What happened

According to the advisory, Netty's OcspClient does not currently validate that the CertificateID in an OCSP response matches the requested CertificateID. This oversight appears to allow a bad actor to bypass revocation checks for any certificate by replaying a GOOD status response issued for an unrelated certificate.

This vulnerability, tracked as GHSA-272M-GCWP-MPWG, is under investigation. Software engineers using Netty should monitor for patches and be prepared to upgrade to a fixed version once it becomes available. The primary sources should be consulted for the most current information and recommendations.

As this is an early warning, the full scope and impact of the vulnerability are not yet confirmed. Engineers are advised to stay informed through official channels and apply patches as soon as they are released.

How 0Day mitigates this

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