CVE-2026-47692
Description
A flaw was found in Envoy. The PROXY Protocol v2 header generator can emit data beyond the maximum allowed length, leading to a mismatch between the actual bytes sent and the length specified in the header. An attacker on an adjacent network could exploit this to smuggle bytes into upstream requests. This could potentially bypass security mechanisms or lead to unexpected behavior in how requests are processed.
Statement
Moderate: Envoy's PROXY Protocol v2 header generator can emit TLVs exceeding the maximum length, leading to a mismatch in bytes written and the header's length field. This flaw allows for up to 65 KB of attacker-controlled data to be smuggled into the upstream request, potentially bypassing security controls or corrupting data. This primarily affects deployments where Envoy is configured to use PROXY Protocol v2.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
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 | 4.8 | 4.3 | 4.8 |
| Attack Vector | Adjacent Network | Adjacent Network | Adjacent Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | High | None | High |
| User Interaction | None | None | None |
| Scope | Changed | Unchanged | Changed |
| Confidentiality | None | None | None |
| Integrity Impact | Low | Low | Low |
| Availability Impact | Low | None | Low |
Vector
Red Hat: CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:L
NVD: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
cve.org: CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:L
Understanding the Weakness (CWE)
Confidentiality,Integrity
Technical Impact: Read Memory; Modify Memory; Varies by Context
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