CVE-2026-85594: Traefik v3.7.1 crossProviderNamespaces Bypass via Service Middleware
Vulnerability summary
CVE-2026-85594 is a critical (CVSS 9.8) vulnerability in traefik. EPSS estimates a 0.48% chance of exploitation in the next 30 days, higher than 41.2% of scored vulnerabilities. 1 public exploit is recorded.
Public exploit (GitHub, Date unknown)
Source freshness unavailable
How is this decided?Timeline
- 04-09-2026PublishedVulnerability first disclosed.
- 08-10-2026Last modifiedVulnerability information updated.
Description
Traefik versions from v3.7.1 fail to enforce crossProviderNamespaces restrictions on the traefik.ingress.kubernetes.io/service.middlewares Service annotation in the Kubernetes Ingress provider. A namespace-limited tenant excluded from the allowlist can attach an operator-owned middleware to its Service, and if that middleware injects backend credentials, recover them at a controlled backend.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · WolfiEcosystem advisory · calculated7.0HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
- OSV · ChainguardEcosystem advisory · calculated7.0HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
- NVDNIST7.0HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS trend
Probability
0.48%
Chance of exploitation in the next 30 days
Percentile
41%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.48% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
1 foundTraefik
Maturity: poc
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Chainguard2 products
- traefik-2.11All versions (No fix recorded)
- traefik-3.6All versions (No fix recorded)
Traefik1 product
- traefik≥ 3.7.1, ≤ 3.7.12 | < 3.7.11
Wolfi1 product
- traefik-3.6All versions (No fix recorded)
3 vendors · 4 products
References
4 links- github.com/traefik/traefik/security/advisories/GHSA-m6wx-622r-48r9Vendor AdvisoryAdvisoryExploitPatch
- www.vulncheck.com/advisories/traefik-3.7.1-crossprovidernamespaces-bypass-via-service-middlewareThird Party AdvisoryAdvisory
