CVE-2026-59313 in Spring Framework
Summary
by MITRE • 08/27/2026
Spring MVC applications using the functional web framework are vulnerable to stream corruption when using Server-Sent Events (SSE). Spring Framework 7.0.0 - 7.0.8 Spring Framework 6.2.0 - 6.2.19 Spring Framework 6.1.0 - 6.1.28 Spring Framework 6.0.0 - 6.0.30 Spring Framework 5.3.0 - 5.3.49
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Analysis
by VulDB Data Team • 08/27/2026
The vulnerability identified in the specified versions of the Spring Framework affects applications utilizing the functional web framework, specifically when implementing Server-Sent Events (SSE). This issue manifests as stream corruption, a critical flaw that compromises the integrity and reliability of data transmission between the server and client. The affected version ranges include Spring MVC 7.0 through 7.0.8, 6.2 through 6.2.19, 6.1 through 6.1.28, 6.0 through 6.0.30, and 5.3 through 5.3.49. This widespread impact across multiple major release lines indicates a systemic issue within the core handling of SSE streams in the functional web model rather than an isolated bug in a single component.
From a technical perspective, Server-Sent Events rely on a persistent HTTP connection where the server pushes real-time updates to clients over a text-based stream. The corruption likely stems from improper buffer management or encoding errors during the serialization and transmission of event data. When the framework processes SSE payloads, it may fail to correctly handle boundary conditions, character escaping, or chunked transfer coding mechanisms inherent in long-lived connections. This can result in malformed HTTP responses where the client receives truncated messages, garbled text, or unexpected end-of-stream signals prematurely. Such corruption disrupts the continuous flow of data required for real-time applications like live dashboards, notification systems, and collaborative tools that depend on Spring MVC's functional endpoints to deliver timely information.
The operational impact of this vulnerability is significant for any production environment relying on SSE for critical business logic or user-facing features. Clients experiencing stream corruption may fail to render updates correctly, leading to stale data displays or complete connection drops requiring manual refreshes. In high-throughput scenarios, the accumulation of corrupted streams can lead to resource exhaustion as clients repeatedly attempt reconnections while servers struggle with malformed state management. Furthermore, if the application logic assumes successful delivery based on HTTP status codes rather than actual payload integrity, downstream services might process incomplete data structures, potentially causing cascading failures in microservices architectures that consume these SSE feeds.
This flaw aligns closely with CWE-20 Improper Input Validation and CWE-756 Missing Correct Implementation of Custom Encoding Scheme within the Common Weakness Enumeration taxonomy. The root cause typically involves a failure to properly encode or decode data according to the SSE specification, which mandates specific formatting rules for event streams including proper escaping of newlines and colons. Additionally, from an adversary perspective, if this corruption can be triggered maliciously through crafted inputs, it could facilitate Denial-of-Service attacks by exhausting server resources or client bandwidth, mapping partially to MITRE ATT&CK technique T1499 Endpoint Denial of Service via application layer exhaustion.
Mitigation strategies primarily involve upgrading the Spring Framework to a patched version outside the affected ranges listed above. For organizations unable to upgrade immediately due to legacy constraints, implementing strict input validation on all data passed into SSE endpoints is essential. Developers should ensure that special characters such as newlines and colons are correctly escaped before being written to the response stream. Additionally, monitoring server logs for HTTP 400 Bad Request or connection reset errors can help detect instances of corruption in real-time. Applying a reverse proxy configuration with strict timeout settings may also mitigate some effects by preventing long-lived corrupted connections from consuming excessive resources until an upgrade is performed.