CVE-2026-41700: Spring for GraphQL WebSocket Cross-Site Hijacking Vulnerability

Technical summary

CVE-2026-41700 is a Cross-Site WebSocket Hijacking (CSWSH) vulnerability affecting Spring for GraphQL's WebSocket transport implementation. The vulnerability exists because WebSocket connections from browsers automatically include authentication credentials (cookies, tokens, etc.) in the initial handshake, but lack the same cross-origin protections that standard HTTP requests enforce. When a user authenticated to a GraphQL endpoint visits an attacker-controlled site, that site can establish a WebSocket connection to the target GraphQL service using the victim's credentials. The attacker can then send arbitrary GraphQL operations through this hijacked connection. This is classified as CWE-346 (Origin Validation Error) and affects versions 1.0.0–1.0.6, 1.3.0–1.3.8, 1.4.0–1.4.5, and 2.0.0–2.0.3 of Spring for GraphQL.

Business impact

Organizations running Spring for GraphQL with WebSocket transport face the risk of unauthorized data access and modification. An attacker exploiting this vulnerability could read sensitive information exposed through the GraphQL API, modify or delete data, perform unauthorized transactions, or escalate privileges—all using a legitimate user's credentials. The attack requires no special network access (network-adjacent or better) and can be automated at scale by hosting a malicious website and promoting it to target users. From a compliance perspective, unauthorized data access via compromised sessions may trigger breach notification and reporting obligations. Business continuity could be affected if attackers perform destructive operations through hijacked connections.

Affected systems

Spring for GraphQL versions 1.0.0 through 1.0.6, 1.3.0 through 1.3.8, 1.4.0 through 1.4.5, and 2.0.0 through 2.0.3 are affected. The vulnerability only impacts applications that have explicitly enabled WebSocket transport for GraphQL. Applications using only HTTP-based GraphQL (standard REST or HTTP subscriptions without WebSocket) are not affected. Organizations should inventory their Spring for GraphQL deployments and determine which ones have WebSocket transport enabled.

Exploitability

This vulnerability has a CVSS score of 8.1 (HIGH), with a network attack vector, low complexity, and no special privileges required—only user interaction. It is not currently listed in CISA's Known Exploited Vulnerabilities (KEV) catalog. However, the attack is straightforward to execute: an attacker needs only to host a web page containing JavaScript that initiates a WebSocket connection to the target GraphQL endpoint. The barrier to weaponization is low. Once exploited, the attacker gains the full authority of the victim user, making the impact substantial. Real-world exploitation would likely target authenticated users who have access to valuable or sensitive GraphQL operations.

Remediation

Apply vendor patches immediately. VMware has released patched versions for all affected release lines. Verify the exact patch version against the official Spring for GraphQL security advisory. As an interim mitigation, disable WebSocket transport if it is not required for your application's functionality. Additionally, implement strict Content Security Policy (CSP) headers to limit cross-origin WebSocket connections, and enforce authentication token rotation to minimize the window of opportunity for hijacked sessions. Consider adding Server-Sent Events (SSE) as an alternative to WebSocket for subscription-based use cases if suitable for your architecture.

Patch guidance

Check the official VMware Spring for GraphQL security advisory for the exact patched versions corresponding to your current version. Patches are expected to be available for all affected version lines. Apply patches during the next available maintenance window, prioritizing production systems that expose sensitive GraphQL operations. Before patching, test the update in a staging environment to verify compatibility with your application. If you are on an unsupported version (prior to 1.0.0), upgrade to a currently supported release. Verify after patching that WebSocket transport is functioning correctly and that your application's GraphQL subscriptions or real-time features continue to work as expected.

Detection guidance

Monitor WebSocket connections to your GraphQL endpoints for suspicious patterns: (1) WebSocket handshakes originating from unexpected origins (check the Origin header), (2) authenticated WebSocket sessions followed by unusual GraphQL operations inconsistent with normal user behavior, (3) spike in failed or unauthorized GraphQL operations. Implement logging of WebSocket connection establishment, including the source Origin header and authenticated user identity. Review GraphQL operation logs for commands issued from hijacked sessions. Security tools and WAF solutions with WebSocket inspection capabilities can help detect cross-origin WebSocket handshakes. Enable audit logging on your GraphQL layer to track who performed what operations and when.

Why prioritize this

This vulnerability merits immediate prioritization due to its HIGH severity score (8.1), ease of exploitation, and the high potential impact. The attack requires only user interaction (visiting a malicious site) and no special network access, making it practical for broad-scale campaigns. The victim's credentials grant the attacker full GraphQL access, potentially leading to data breaches or service disruption. It is not yet in the KEV catalog, but the simplicity of exploitation suggests real-world attacks are likely. All affected Spring for GraphQL instances with WebSocket enabled should be patched urgently.

Risk score, explained

The CVSS 3.1 score of 8.1 (HIGH) reflects: (1) network-based attack requiring only a user's browser, (2) low attack complexity—no special conditions or configurations needed, (3) no privileges required to initiate the attack, (4) user interaction required (visiting a malicious site), (5) high confidentiality impact (data exposure), (6) high integrity impact (unauthorized modifications), and (7) no availability impact. The score does not assume the vulnerability is already exploited in the wild, but the simplicity and high potential impact justify the HIGH rating.

Frequently asked questions