CVE-2026-88878

Traefik v2.8.2 through v3.6 HTTP/3 Timeout Bypass

MEDIUM
5.3
CVSS Score
Published: September 10, 2026 at 01:05 PM UTC
Updated: October 8, 2026 at 04:17 PM UTC
1 product affected across 1 vendorTraefik

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

Traefik is an HTTP reverse proxy and load balancer. In versions >= v2.8.2 through <= v2.11.55 and >= v3.0.0 through <= v3.7.11, the entryPoints.<name>.transport.respondingTimeouts settings — notably readTimeout, which is enabled by default at 60s — are not applied to the HTTP/3 request path. readTimeout is enforced as a deadline on the underlying TCP connection, which cannot be applied to a QUIC stream, and Traefik's HTTP/3 server is constructed without any timeout. As a result, on entry points with HTTP/3 enabled, an unauthenticated remote client that trickles request body bytes can hold a request open indefinitely and, with it, one upstream connection per request, exhausting bounded backend connection pools and causing denial of service. The issue was introduced in v2.8.2 when a quic-go API change removed the embedded http.Server that carried these timeouts. Fixed in v2.11.56 and v3.7.12.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

2.8.2 ≤ v ≤ 3.7.132.8.2 ≤ v < 2.11.563.0.0 ≤ v ≤ 3.7.133.0.0 ≤ v < 3.7.12*2.8.23.0.0
Affected range stops below 2.11.56, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.7.12, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (2)

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusANALYZED
CWE
CWE-770

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