# CVE-2026-118681: go-chi chi before 5.5.0 Authentication Bypass via SupressNotFound Middleware

Status: published. Published: 2026-10-28. Updated: 2026-11-03.

go-chi chi before 5.5.0 contains an authentication bypass in middleware.SupressNotFound, which calls Match with the live routing context and leaves a mounted router's parameter and child suffix in place for dispatch against the outer router. Unauthenticated attackers can request a mounted path whose suffix matches an outer public route, skipping the mounted authentication middleware and retrieving tenant-scoped data when that outer handler trusts the retained mount parameter.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- go-chi / chi (github.com/go-chi/chi/v5): ≥ 0; < 5.5.0 (affected, semver); 5.5.0 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 6.3 (medium); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 3.7 (low); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: 0.24% as of 2026-11-02; percentile 15.61%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-288

## Exploit evidence

- exploit: https://github.com/go-chi/chi/security/advisories/GHSA-rqrp-8cg2-5958 (ADP: CISA-ADP)

## References

- https://github.com/go-chi/chi/security/advisories/GHSA-rqrp-8cg2-5958 (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/go-chi-chi-before-5.5.0-authentication-bypass-via-supressnotfound-middleware (CNA: VulnCheck; third-party-advisory)

- https://github.com/go-chi/chi/security/advisories/GHSA-rqrp-8cg2-5958 (ADP: CISA-ADP; exploit)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-118681; retrieved 2026-11-03; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-118681; retrieved 2026-11-03; source updated Not reported

Revision: 5f81cdcf4d69271d7c9ecd7dad39c21f4de9d4cac40a558b2abc93ce94ceb4bc

Canonical: https://y2.dev/cve/CVE-2026-118681

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