Username enumeration via BasicAuth response timing
Published Mar 20, 2026 · Updated Mar 20, 2026
Timing discrepancy in Traefik Proxy's BasicAuth middleware allows remote attackers to enumerate valid usernames over HTTP. Credential validation returns immediately for unknown usernames but performs a costly bcrypt comparison for known usernames, exposing a measurable response-time gap. Exposure requires BasicAuth on a reachable protected endpoint; the result reveals account validity without granting authentication or direct data access.
Summary
What happened
Timing discrepancy in Traefik Proxy's BasicAuth middleware allows remote attackers to enumerate valid usernames over HTTP. Credential validation returns immediately for unknown usernames but performs a costly bcrypt comparison for known usernames, exposing a measurable response-time gap. Exposure requires BasicAuth on a reachable protected endpoint; the result reveals account validity without granting authentication or direct data access.
The record
- CVE
- CVE-2026-32595
- Published
- Mar 20, 2026
- Updated
- Mar 20, 2026
- Vendor
- Traefik Labs
- Product
- Traefik Proxy
- Classifications
- CWE-208, T1087
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 20, 2026CVE publishedPublication date reported by the CVE source.
- Mar 20, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 2.11.41
- Affected versionversion=>= 3.0.0-beta1, < 3.6.11
- Affected versionversion=>= 3.7.0-ea.1, < 3.7.0-ea.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- BasicAuth timing enumeration proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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