CVE-2026-47890 Overview
CVE-2026-47890 affects Spring MVC and WebFlux applications that combine Server-Sent Events (SSE) with view fragments. The flaw allows stream corruption in the SSE response, disrupting the framing and ordering of events delivered to clients. Applications rendering view fragments over an SSE endpoint may emit malformed event streams that mix or truncate payloads across events. The issue impacts Spring Framework versions 7.0.0 through 7.0.8 and 6.2.0 through 6.2.19. Details are documented in the Spring Security Advisory CVE-2026-47890.
Critical Impact
Stream corruption in SSE endpoints can cause clients to receive malformed, interleaved, or truncated event payloads, degrading application integrity and downstream processing.
Affected Products
- Spring Framework 7.0.0 through 7.0.8
- Spring Framework 6.2.0 through 6.2.19
- Spring MVC and Spring WebFlux applications using SSE with view fragments
Discovery Timeline
- 2026-08-27 - CVE-2026-47890 published to the National Vulnerability Database (NVD)
- 2026-08-27 - Last updated in NVD database
Technical Details for CVE-2026-47890
Vulnerability Analysis
Spring MVC and WebFlux support returning view fragments for progressive rendering. When these fragments are streamed through a Server-Sent Events endpoint, the framework must emit each fragment as a discrete data: event delimited by a blank line. The vulnerability results in incorrect framing of the SSE stream when view fragments are used, producing output that no longer conforms to the SSE specification. Consumers relying on well-formed events may receive concatenated payloads, misaligned event boundaries, or partial data.
The defect is a stream-integrity issue rather than a memory corruption or code execution flaw. It affects the correctness of data delivered to clients and any downstream logic that parses SSE frames, including browser EventSource clients and reactive gateways. Applications combining templated fragments with reactive streams are the primary exposure surface.
Root Cause
The root cause resides in the handling logic that renders view fragments to the SSE response body in the affected Spring Framework versions. Fragment output is not consistently terminated and encoded per the text/event-stream framing rules, allowing content from one fragment to bleed into the framing of the next. Refer to the Spring Security Advisory CVE-2026-47890 for authoritative technical detail.
Attack Vector
Exploitation requires an application that exposes an SSE endpoint returning view fragments. A client consuming the corrupted stream will observe malformed events. Whether an external attacker can influence stream corruption to produce a security-relevant outcome depends on the application. The advisory does not confirm remote code execution, authentication bypass, or privilege escalation. No public exploit is reported.
No verified proof-of-concept code is available. See the Spring Security Advisory CVE-2026-47890 for reproduction guidance from the vendor.
Detection Methods for CVE-2026-47890
Indicators of Compromise
- SSE responses from Spring endpoints containing malformed data: framing or missing blank-line delimiters between events
- Client-side EventSource parse errors or unexpected message payloads on endpoints that stream view fragments
- Application logs showing rendering exceptions from SseEmitter, ServerSentEvent, or reactive Flux<ServerSentEvent<?>> handlers
Detection Strategies
- Inventory Spring Framework dependencies and flag any deployment on 7.0.0–7.0.8 or 6.2.0–6.2.19 that exposes SSE endpoints returning view fragments
- Add integration tests that consume SSE endpoints and validate strict conformance to the text/event-stream format
- Review controller code for produces = MediaType.TEXT_EVENT_STREAM_VALUE combined with view fragment return types
Monitoring Recommendations
- Monitor HTTP response content-type and error rates on SSE routes, alerting on client disconnect spikes or parse failures
- Capture and inspect a sample of SSE responses through an application gateway to verify event framing integrity
- Track Spring Framework version telemetry across build pipelines to identify unpatched services
How to Mitigate CVE-2026-47890
Immediate Actions Required
- Identify all services running affected Spring Framework versions using SSE with view fragments
- Upgrade Spring Framework to a fixed release as documented in the Spring Security Advisory CVE-2026-47890
- Restrict or disable SSE endpoints that render view fragments until patched
Patch Information
Upgrade to the fixed Spring Framework versions listed in the vendor advisory. Consult the Spring Security Advisory CVE-2026-47890 for the exact fixed version numbers and release notes. After upgrading, rebuild and redeploy affected Spring MVC and WebFlux applications, then re-run SSE integration tests to confirm event framing conformance.
Workarounds
- Avoid returning view fragments from SSE endpoints; return ServerSentEvent<String> or serialized DTOs instead
- Serialize fragment content server-side into fully rendered strings before emitting each SSE event
- Place a reverse proxy or gateway rule that validates SSE framing before forwarding to clients
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
