Answer in brief
CVE-2026-48491 records a High severity (CVSS 10.0) vulnerability in Traefik: SNICheck ignores wildcard TLSOptions mappings, allowing domain-fronted mTLS bypass. The current sources do not mark it as known exploited. The current feed maps traefik/traefik (generic), github.com/traefik/traefik/v2 (go), github.com/traefik/traefik/v2 (go), github.com/traefik/traefik/v3 (go) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 10.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps traefik/traefik (generic), github.com/traefik/traefik/v2 (go), github.com/traefik/traefik/v2 (go), github.com/traefik/traefik/v3 (go) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| traefik/traefikgeneric | >= 3.7.0, < 3.7.3 | Not reported |
| github.com/traefik/traefik/v2go | >=0 <2.11.48 | 2.11.48 |
| github.com/traefik/traefik/v2go | <2.11.48 | 2.11.48 |
| github.com/traefik/traefik/v3go | >=3.7.0 <3.7.3 | 3.7.3 |
| github.com/traefik/traefik/v3go | >=3.7.0,<3.7.3 | 3.7.3 |
| Traefikgo | >=3.7.0,<=3.7.1 | 3.7.3 |
| Traefikgo | >=3.7.0 <3.7.3 | 3.7.3 |
Published upstream
Jun 23, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 2, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 19, 2026
Traefik 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.
Quoted source text, attributed separately from HOL analysis.