Network security visualization
Security Alert

Critical Brotli Vulnerability: What You Need to Know About CVE-2026-111497

A critical vulnerability in the widely used Brotli compression library could put applications and systems across a number of technology environments at risk.

The vulnerability, identified as CVE-2026-111497 and commonly referred to as Brotli2Shell, Node2Shell, or HTTP2Shell, should be treated as a high-priority security issue.

Why This Matters

CVE-2026-111497 is a vulnerability in the Brotli decoder. A successful attack against a vulnerable application could cause the application to crash, expose information from memory, or potentially allow an attacker to execute unauthorized code.

The vulnerability has been added to CISA's Known Exploited Vulnerabilities catalog, and exploitation attempts have been reported.

Organizations should review their environments promptly to understand whether potentially vulnerable systems or applications are present.

What Technologies May Be Affected?

Because Brotli is used across a broad range of software, this is not limited to one platform or application. Environments that may require review include applications or services involving:

  • Node.js
  • .NET
  • PowerShell
  • Python packages and HTTP clients
  • Bun
  • Envoy Proxy
  • Istio

The presence of one of these technologies does not automatically mean a system is vulnerable. Organizations should determine whether affected Brotli components are being used and review the security guidance provided by the appropriate software vendor.

Internet-Facing Systems Deserve Particular Attention

Organizations should give priority to externally accessible applications and services that process Brotli-compressed data. Any application that processes attacker-controlled data using a vulnerable Brotli decoder could potentially be at risk.

What Should Organizations Do?

IT and security teams should begin by understanding where Brotli may be used in their environment and whether affected versions are present.

  1. Identify potentially affected systems. Review applications and services using technologies that may include vulnerable Brotli components.
  2. Determine whether affected versions are present. Review the latest security guidance and documentation from the appropriate software vendors.
  3. Prioritize internet-facing systems. Give additional attention to applications and services processing externally supplied compressed data.
  4. Apply available security updates. Follow vendor guidance and deploy appropriate updates as soon as practical.
  5. Evaluate temporary protections when necessary. If an update cannot be applied immediately, review vendor-supported options for restricting or disabling Brotli processing where appropriate.

Not Sure If Your Environment Is Exposed?

Vulnerabilities involving widely used software components can make it difficult to know exactly where your organization is exposed. EDCi can help you review your environment, understand potential exposure, and determine the right next steps for your organization.

Talk to an EDCi Security Expert

Additional Resources

Organizations should continue monitoring security guidance from CISA's Known Exploited Vulnerabilities (KEV) catalog and the vendors responsible for the technologies used in their environments.