Traefik: BasicAuth singleflight coalescing reintroduces an unauthenticated username-enumeration timing oracle (CVE-2026-88010) | HOL Guard CVE

Medium · CVSS 6.3CVE-2026-88010

Traefik: BasicAuth singleflight coalescing reintroduces an unauthenticated username-enumeration timing oracle

Answer in brief

CVE-2026-88010 records a Medium severity (CVSS 6.3) vulnerability in Traefik: BasicAuth singleflight coalescing reintroduces an unauthenticated username-enumeration timing oracle. The current sources do not mark it as known exploited. The current feed maps traefik/traefik (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 22, 2026Updated Sep 22, 2026Source checked Sep 22, 2026First seen by HOL Sep 22, 2026Material review Sep 22, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 6.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

CVSS is 6.3. 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.

Affected scope and exposure questions

The current feed maps traefik/traefik (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
traefik/traefikgeneric	>= 3.6.11, < 3.7.13	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for traefik/traefik.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Sep 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 22, 2026

Sources and claim methodology

Upstream source description

Traefik is an open source HTTP reverse proxy and load balancer. From 3.6.11 until 3.7.13, checkPassword in pkg/middlewares/auth/basic_auth.go constructs the BasicAuth singleflight key from the submitted password and stored secret. Concurrent requests for absent usernames therefore coalesce on one key while configured usernames perform separate password hashes, creating an unauthenticated timing discrepancy that reveals whether a username exists. Sequential checks remain cost-equalized, Traefik v2 and Digest authentication are not affected, and the issue does not disclose credentials or bypass authentication. This issue is fixed in version 3.7.13.

Quoted source text, attributed separately from HOL analysis.