External risk intelligence

Spring MVC Server-Sent Events Stream Corruption Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-59313

Spring MVC is a widely used framework for building web applications and APIs that are commonly deployed as internet-facing services. While specific exposure depends on the implementation of Server-Sent Events, the framework's primary role in hosting web endpoints makes public internet reachability a common deployment pattern.

Vmware Spring Framework

5.3.0 to 5.3.496.0.0 to 6.0.306.1.0 to 6.1.286.2.0 to 6.2.197.0.0 to 7.0.8

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability has been identified in Spring MVC applications utilizing the functional web framework when processing Server-Sent Events. This issue could allow for stream corruption, potentially impacting application integrity and availability. The main concern is confirming if your Spring applications are affected and to what extent.

Affects web applications using specific event streaming.
Matters because it can corrupt application data streams.
Confirm if your Spring MVC applications are exposed.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending specially crafted requests to a Spring MVC application that uses Server-Sent Events. This could lead to stream corruption, potentially allowing for significant impact on confidentiality, integrity, and availability if the application is reachable over the network.

No authentication or user interaction required.
Triggered by sending malicious requests.
High risk to data and application.

Live Threat

Current exploitation, exposure, and threat context

Spring MVC applications that use the functional web framework and Server-Sent Events (SSE) could be vulnerable to stream corruption. This could potentially affect the integrity and availability of the application's services when the SSE functionality is utilized.

Application services and data integrity.
Via corrupted SSE streams.
Service disruption and data corruption.

Operational Fix

Recommended remediation, mitigation, and detection steps

Application owners and platform teams are likely responsible for addressing this vulnerability in Spring MVC applications leveraging the functional web framework, particularly if Server-Sent Events are exposed externally. The first practical step is to inventory all instances of the affected Spring Framework versions, confirm external reachability and business criticality, identify the specific application owner, and then prioritize remediation efforts.

Confirm ownership and assess exposure.
Verify affected application inventory.
Plan risk-based remediation.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the Spring Framework and how does it relate to CVE-2026-59313?

The Spring Framework is a popular, comprehensive Java platform used by developers to build diverse web applications and APIs. CVE-2026-59313 specifically impacts Spring MVC, a module within this framework designed to handle web requests. The vulnerability is limited to applications that utilize the framework's functional web capabilities to implement Server-Sent Events, which are used to push real-time data updates from a server to a web browser.

How does stream corruption occur in this vulnerability?

This vulnerability is classified as CWE-93, which involves improper neutralization of CRLF sequences. In the context of CVE-2026-59313, it means the application fails to properly sanitize input data within Server-Sent Events. An attacker can manipulate this stream, causing the underlying communication protocol to misinterpret the data flow. This disruption can interfere with how the application processes information, leading to the corruption of data streams.

What triggers this security flaw?

The flaw is triggered when an attacker sends specially crafted network requests to an application that uses the affected functional web framework to support Server-Sent Events. Notably, this does not require the attacker to have an existing account, nor does it require any specific interaction from a legitimate user. If an application does not use Server-Sent Events, or if it uses a different part of the Spring Framework not involving this specific functional streaming, it is not susceptible to this trigger.

Is my application at risk?

According to Halo Surface Signal, the risk is higher if your application is internet-facing, as Spring MVC is commonly deployed to host public web endpoints. Since the vulnerability is reachable over the network without authentication, services exposed to the public internet are a primary concern. You should prioritize assessing applications that perform real-time data streaming and are reachable by external traffic, as these represent the most likely path for an external attacker.

How should I begin addressing this issue?

Start by identifying all applications in your environment that rely on the affected versions of the Spring Framework. Once you have an inventory, confirm which of these specifically implement Server-Sent Events via the functional web framework. After verifying these details, determine which applications are critical to your business and are accessible over the network. Use this information to coordinate with your technical teams to plan and prioritize your update process.

References

spring.io/security/cve-2026-59313

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.