CVE-2026-47863
Description
A flaw was found in Reactor Core. Applications using the Flux.bufferTimeout operator with fairBackpressure enabled are vulnerable to a Denial of Service (DoS) condition. This occurs when upstream components deliver items during an active flush, causing the processing pipeline to permanently hang and making the application unresponsive.
Statement
Moderate: Applications using the Flux.bufferTimeout operator with fairBackpressure enabled in Reactor Core are vulnerable to a Denial of Service condition. This impact is considered Moderate because exploitation requires a specific, non-default application configuration or usage pattern.
Mitigation
To mitigate this issue, applications should avoid using the `Flux.bufferTimeout` operator with `fairBackpressure` enabled. Review application code for instances where `fairBackpressure` is explicitly enabled with `Flux.bufferTimeout` and consider alternative buffering strategies or disabling `fairBackpressure` if it is not strictly required for the application's functionality.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.9 | 7.5 | 5.9 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | Low | High |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | None |
| Integrity Impact | None | None | None |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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