CVE-2026-56821
An attacker can exploit multiple vulnerabilities in Netty to bypass security checks, manipulate requests or headers, circumvent certificate checks, and cause a denial of service.
CSIRTS triage
- What
- Multiple vulnerabilities can bypass security checks, manipulate requests, circumvent certificate checks, and cause denial of service.
- Who is affected
- Attackers can exploit these vulnerabilities in Netty deployments.
- Urgency
- Remediation is high urgency due to the severity and potential for exploitation.
- Action
- Update to the latest version of Netty to fix these vulnerabilities.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.14% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 4% of all EPSS-scored CVEs.
Advisory coverage (3)
- high[NEW] [high] Netty: Multiple vulnerabilitiescert-bund · 2026-07-30
- highCVE-2026-56821: Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.13…nvd · 2026-07-29
- highGHSA-g7hg-vrcf-mvmr: Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidatorghsa · 2026-07-22
External references
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[](https://www.csirts.com/cve/CVE-2026-56821)