Axios HTTP/2 Flaws Enable SSRF Control Bypass and Node.js Denial of Service

Axios has disclosed two high-severity vulnerabilities in its HTTP/2 implementation that could allow attackers to bypass outbound network controls or crash vulnerable Node.js applications. The flaws affect Axios versions 1.13.0 through 1.19.x and have been fixed in version 1.20.0

The first issue, tracked as GHSA-3pq3-5fj3-cg6v and CVE-2026-101898, affects Axios applications that use HTTP/2 requests alongside custom DNS lookup functions or proxy settings.

Axios may fail to apply caller-supplied config. It may fail to apply caller-supplied DNS lookup policies, explicit proxy settings, or proxy configuration inherited from environment variables before creating an HTTP/2 connection.

This creates a server-side request forgery risk in applications that accept user-controlled URLs. Security teams commonly use a custom DNS resolver to block internal addresses, cloud metadata services, localhost targets, or private network ranges.

Other deployments force outbound traffic through an inspection proxy. Under the vulnerable HTTP/2 code path, Axios can connect directly to a destination instead of honoring those protections.

Axios HTTP/2 Flaws

An attacker could abuse the flaw when an application passes a user-influenced destination into Axios with httpVersion: 2. For example, a web service designed to fetch external URLs may use a DNS allowlist to prevent requests to 127.0.0.1, RFC1918 networks, or cloud metadata endpoints.

If the service switches to the affected HTTP/2 adapter, Axios could bypass the custom lookup or proxy route and send a direct request to a restricted resource.

The second issue, GHSA-542g-h47m-68v8 and CVE-2026-101901, can cause denial-of-service in Node.js applications. Axios did not install adequate error handling for a ClientHttp2Session during HTTP/2 session initialization or reuse.

If that session emits an error event, the event may escape Axios’s normal Promise rejection handling and become an uncaught exception.

In Node.js, an unhandled error event can terminate the running process. Therefore, an attacker who can influence a request flow that creates or reuses an Axios HTTP/2 session may be able to force an affected service offline.

The practical risk is highest in applications that use Axios to retrieve attacker-controlled URLs, call external integrations, process webhooks, or proxy requests to user-specified hosts.

The Axios advisory covers two high-severity flaws following the introduction of HTTP/2 support in its Node.js HTTP adapter in version 1.13.0.

Organizations should upgrade Axios to version 1.20.0 or later immediately. Until patching is complete, teams should turn off HTTP/2 requests by removing httpVersion: 2 or using HTTP/1.1.

Defenders should also review applications that fetch user-supplied URLs, validate destination hosts before initiating requests, maintain egress filtering outside the application layer, and monitor outbound connections for unexpected internal or metadata-service access.

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