CVE-2025-64763
Description
A flaw was found in Envoy. This vulnerability allows a de-synchronized CONNECT tunnel state via accepting client data before issuing a 2xx response and forwarding it to the upstream TCP (Transmission Control Protocol) connection when configured in TCP (Transmission Control Protocol) proxy mode to handle CONNECT requests.
Statement
This vulnerability is rated Moderate for Red Hat. Envoy, when operating in TCP proxy mode for CONNECT requests, forwards client data before a 2xx response. This can lead to a de-synchronized CONNECT tunnel state if an upstream proxy rejects the tunnel establishment. This behavior is enabled by default in affected versions of OpenShift Service Mesh.
Mitigation
To mitigate this issue, set the `envoy.reloadable_features.reject_early_connect_data` runtime flag to reject CONNECT requests that send data before a 2xx response. This configuration change may require a service reload or restart to take effect.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | 5.3 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | Low | Low | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
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