CVE-2026-108859
Description
A flaw was found in mcp-go. The HTTP server implementation does not restrict the size of incoming HTTP POST request bodies before buffering them into memory. A remote, unauthenticated attacker can exploit this vulnerability by sending excessively large or multiple concurrent requests, causing memory exhaustion and leading to a Denial of Service (DoS) when the server crashes.
Statement
This vulnerability is rated as having an Important severity because an unauthenticated remote attacker can cause an immediate denial of service by exhausting host memory without requiring privileges or user interaction. In affected Red Hat products, such as Red Hat OpenShift distributed tracing and Red Hat Connectivity Link, applications exposing the streamable HTTP endpoint to untrusted network traffic can be terminated by out-of-memory errors when processing oversized payloads. The vulnerability solely impacts service availability, with no compromise to data confidentiality or integrity.
Mitigation
Restrict network exposure of the affected service to trusted clients or place it behind an intermediate reverse proxy or ingress controller that enforces strict HTTP request body size limits.
1. Firewall configuration (for standalone host deployments):
Limit access to the listening port to trusted subnets:
firewall-cmd --permanent --zone=trusted --add-source=<TRUSTED_IP_OR_CIDR>
firewall-cmd --reload
2. OpenShift / Kubernetes environments:
Apply an OpenShift NetworkPolicy to restrict ingress traffic targeting the affected pods exclusively to authorized namespaces or ingress components. Additionally, configure ingress controllers or reverse proxies to limit maximum client request body sizes, dropping oversized POST requests before they reach backend services.
Caveats:
Restricting access to trusted networks will prevent unauthorized or external clients from accessing the service. Setting strict payload thresholds at the proxy layer may reject legitimate client requests that exceed the defined maximum size.
Warning:
Running `firewall-cmd --reload` reloads active firewall configurations and can temporarily disrupt existing network connections.
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 | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: 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:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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