high CVSS 7.5 EPSS 0.77%

CVE-2023-54365·Traefik vulnerability

Traefik before 2.10.5 and 3.0.0-beta4 is affected by a denial-of-service vulnerability in HTTP/2 request handling inherited from the Go standard library's HTTP/2 implementation (CVE-2023-44487 / CVE-2023-39325, the 'Rapid Reset' technique). A remote attacker can rapidly create and cancel HTTP/2 streams to exhaust server resources and cause service unavailability.

Severity
high
Software
Traefik
Fixed in
2.10.5
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.77% — higher than 54% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2023-54365 scores 7.5 on CVSS, so a successful attack would be serious — but at 0.77%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 3.0.0-beta1

Until: 2.10.5

Fixed in: 2.10.5

How to fix this CVE

Upgrade Traefik to version 2.10.5 or later to patch the HTTP/2 stream handling vulnerability that allows denial-of-service attacks. This update incorporates upstream fixes from the Go standard library to mitigate resource exhaustion from rapid stream creation and cancellation. Organizations running Traefik in production should prioritize this update to prevent potential service disruptions.

sudo dnf update traefik

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST|GET|HEAD|OPTIONS|PUT|DELETE HTTP/2.*RST_STREAM|GOAWAY.*RST_STREAM|multiple stream creation within <1 second followed by immediate RST_STREAM frames

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement HTTP/2 connection limits and stream rate limiting: restrict the maximum number of concurrent streams per connection (e.g., max_concurrent_streams = 50), enforce timeouts on stream creation, and monitor for connections that rapidly open and close streams without sending request bodies.

How to check if you are affected

  1. Check the installed Traefik version: traefik version | grep Version
  2. Verify if your Traefik instance accepts HTTP/2 connections: grep -i 'http2\|h2' /etc/traefik/traefik.yml or check your entrypoint configuration for HTTP/2 enablement
  3. Monitor access logs for patterns of rapid stream requests followed by resets: grep 'RST_STREAM\|GOAWAY' /var/log/traefik/access.log or check metrics for abnormal stream closure rates
  4. Confirm the patch is applied: traefik version and verify the version is >= 2.10.5

FAQ

What is CVE-2023-54365?

This vulnerability allows attackers to send specially crafted HTTP/2 requests that create and immediately cancel multiple streams, consuming server memory and CPU resources until the service becomes unresponsive. It stems from a weakness in Go's HTTP/2 implementation that Traefik inherited.

Is CVE-2023-54365 being actively exploited?

No, this vulnerability is not listed in the CISA KEV catalog and no public exploits are currently available, though the underlying HTTP/2 Rapid Reset technique has been documented in the security community.

What versions of Traefik are affected by CVE-2023-54365?

All versions of Traefik 3.0.0-beta1 through 2.10.4 are vulnerable; versions 2.10.5 and later contain the fix.

How do I check if my server is vulnerable to CVE-2023-54365?

Run 'traefik version' and compare the output to version 2.10.5; if your version is earlier, you are vulnerable. Additionally, confirm HTTP/2 is enabled in your Traefik configuration.

Does Defensia detect CVE-2023-54365?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Traefik is installed on a monitored server, CVE-2023-54365 will appear in your dashboard with remediation steps.

Related Traefik CVEs

CVE-2026-53622CVSS 10Traefik is an HTTP reverse proxy and load balancer. Versions prior to 3.7.3, 3.6.18, and 2.11.51 have a critical vulnerability in Traefik's HTTP/3 (QUIC) TLS configuration selection that allows unauthenticated clients to bypass router-specific mTLS enforcement. When HTTP/3 is enabled on an entrypoint, the TLS handshake selects the applicable TLS configuration through an exact, case-sensitive lookup on the SNI value, which fails to match wildcard host patterns (e.g., *.example.com) or case variants of the configured hostname. Because the handshake falls back to the default TLS configuration — which may not require client certificates — a client can complete the QUIC handshake without presenting a certificate, while the subsequent HTTP routing layer still dispatches the request to a backend protected by a router-specific mTLS policy. The issue affects deployments where HTTP/3 is enabled, a router uses a wildcard Host rule or case-insensitive hostname matching, a router-specific TLSOptions enforces client certificate authentication, and UDP access to the entrypoint is reachable by an attacker. This vulnerability is fixed in versions 3.7.3, 3.6.18, and 2.11.51.
CVE-2026-54763CVSS 10Traefik is an HTTP reverse proxy and load balancer. Prior to v2.11.51, v3.6.22, and v3.7.6, Traefik's BasicAuth, DigestAuth, and ForwardAuth middlewares strip canonical-cased spoofed identity headers before writing Traefik's own value, but do not account for underscore-variant header names, which many backends normalize identically to dashed forms. An attacker able to reach a protected route can inject an underscore-variant header that survives Traefik's stripping and reaches the backend alongside, or on the unauthenticated ForwardAuth authResponseHeaders path instead of, the value Traefik intended to set, spoofing identity or authorization context. This issue is fixed in versions v2.11.51, v3.6.22, and v3.7.6.
CVE-2026-48491CVSS 10Traefik is an HTTP reverse proxy and load balancer. From 3.7.0 until 3.7.3, there is a high severity vulnerability in Traefik's domain-fronting protection (SNICheck) that allows an unauthenticated client to bypass mutual TLS enforced through wildcard router TLSOptions. When a router uses a wildcard host rule such as Host(*.example.com) with stricter TLS options (for example RequireAndVerifyClientCert), SNICheck resolves the TLS options for the HTTP Host header using exact map lookups only and never applies wildcard matching. If another permissive SNI is served on the same entrypoint, an attacker can complete the TLS handshake under the permissive options and then send an HTTP Host header targeting the wildcard-protected backend, reaching it without presenting a client certificate. This affects the regular HTTPS / HTTP-2 path and does not require HTTP/3. This vulnerability is fixed in 3.7.3.
CVE-2026-48020CVSS 10Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.48, 3.6.19, and 3.7.3, there is a high severity vulnerability in Traefik's StripPrefix middleware that allows an unauthenticated attacker to bypass route-level authentication and authorization. When a public router matches on a PathPrefix rule and applies the StripPrefix middleware, a request path containing .. or its percent-encoded form %2e%2e can match the public route at routing time and then, after the prefix is stripped and the path is normalized, resolve to a path served by a separate, authenticated router. As a result, an attacker can reach protected backend paths — such as admin or internal configuration endpoints — without satisfying the authentication middleware attached to the protected router. This vulnerability is fixed in 2.11.48, 3.6.19, and 3.7.3.
CVE-2026-44774CVSS 9.9Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.46, 3.6.17, and 3.7.1, Traefik's Kubernetes Gateway API provider allows a tenant with HTTPRoute creation permissions to expose the REST provider handler, bypassing the providers.rest.insecure=false setting. The Gateway provider accepts any TraefikService backend reference whose name ends with @internal, making it possible to route traffic to rest@internal in addition to the intended api@internal. In shared Gateway deployments where the REST provider is enabled, this allows a low-privileged actor to gain live dynamic configuration write access to Traefik, enabling unauthorized reconfiguration of routers and services. This vulnerability is fixed in 2.11.46, 3.6.17, and 3.7.1.

References

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