CVE-2026-88878
Description
A flaw was found in Traefik, an HTTP reverse proxy and load balancer. When HTTP/3 is enabled, an unauthenticated remote client can exploit a timeout bypass vulnerability by trickling request body bytes. This allows the client to hold a request open indefinitely, exhausting backend connection pools and leading to a denial of service (DoS) for legitimate users.
Statement
A flaw was found in Traefik's HTTP/3 implementation (v2.8.2 through v2.11.55 and v3.0.0 through v3.7.11) where respondingTimeouts settings, specifically readTimeout, are not applied to QUIC streams. On entry points with HTTP/3 enabled, an unauthenticated remote client can trickle request body bytes to keep HTTP/3 streams open indefinitely without triggering timeout deadlines. In environments utilizing affected Traefik components, this allows attackers to exhaust bounded upstream backend connection pools, resulting in a denial of service for legitimate users.
Mitigation
Disable HTTP/3 on all Traefik entry points by removing the entryPoints.<name>.http3 configuration or setting enabled: false. Alternatively, enforce strict request body timeouts and connection limits at an upstream load balancer or network gateway.
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 | 7.5 | N/A | 5.3 |
| 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 | Low |
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:L
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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