CVE-2026-48491

CRITICALNVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 10.0 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 71% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
10.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 10.0Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
10.0
EG Score
10.0CRITICALmedium confidence
EG Risk
60
EG Risk 60/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity100% × 45%
Exploitation0% × 40%
Automatability100% × 15%
EPSS PROB
0.4%
EPSS %ILE
27th
KEV
Not listed

Published

June 16, 2026

Last Modified

September 2, 2026

Advisory Details (6)

Auto-updated Oct 7, 2026
🔬 Proof of concept available. Patch available. Sources: github_release, github, redhat.
redhatMentions a patch (unverified)
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48491.json
redhat

2491923 – (CVE-2026-48491) CVE-2026-48491 Traefik: Traefik: Unauthorized access due to mutual TLS bypass

https://bugzilla.redhat.com/show_bug.cgi?id=2491923
redhatMentions a patch (unverified)

CVE-2026-48491 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

https://access.redhat.com/security/cve/CVE-2026-48491
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:62260
githubMentions a patch (unverified)🟡 PoC Available

SNICheck ignores wildcard TLSOptions mappings, allowing domain-fronted mTLS bypass · Advisory · traefik/traefik · GitHub

https://github.com/traefik/traefik/security/advisories/GHSA-5r4w-85f3-pw66
github_release Patch Available

v3.7.3

Patch available: traefik/traefik v3.7.3

https://github.com/traefik/traefik/releases/tag/v3.7.3

Vendor Advisories for CVE-2026-48491(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatdevspaces/traefik-rhel9:17877567992026-09-01redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(3 across 1 ecosystem)
Go(3)
PackageVulnerable rangeFix by version rangeDependents
github.com/traefik/traefik/v2—
  • every version up to 2.11.48: fixed in 2.11.48
—
github.com/traefik/traefik/v3—
  • 3.7.0 up to 3.7.3: fixed in 3.7.3
—
Traefik—
  • 3.7.0 up to 3.7.3: fixed in 3.7.3
—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 25× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 134 total refreshes for this CVE.

  1. 2026-10-09 20:07 UTCEPSS rescore
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  20. 2026-09-14 07:07 UTCVendor advisory
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  22. 2026-09-14 03:30 UTCVendor advisory
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  6. 2026-09-02 13:37 UTCVendor advisory
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  8. 2026-09-02 12:37 UTCVendor advisory
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Frequently asked(5)

What is CVE-2026-48491?
CVE-2026-48491 is a critical vulnerability published on June 16, 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…
When was CVE-2026-48491 disclosed?
CVE-2026-48491 was first published on June 16, 2026, with the most recent update on September 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-48491 actively exploited?
CVE-2026-48491 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (27th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-48491?
CVE-2026-48491 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2026-48491?
A fix for CVE-2026-48491 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-48491 are linked in the Vendor Advisories panel on this page.

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