CVE-2026-54685Public exploitNetwork attack vector

Username enumeration via pre-bcrypt early return

Published Jul 20, 2026 · Updated Jul 20, 2026

Observable timing discrepancy in FileBrowser Quantum before 1.3.2-beta allows remote attackers to enumerate valid usernames via login requests. The JSONAuth.Auth function looks up the supplied username before password validation and returns immediately on a miss, while a hit runs bcrypt. No authentication or user interaction is required; repeated response-time measurements disclose account names but not passwords or file contents.

CVSS severity5.3
Medium
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Observable timing discrepancy in FileBrowser Quantum before 1.3.2-beta allows remote attackers to enumerate valid usernames via login requests. The JSONAuth.Auth function looks up the supplied username before password validation and returns immediately on a miss, while a hit runs bcrypt. No authentication or user interaction is required; repeated response-time measurements disclose account names but not passwords or file contents.

The record

CVE
CVE-2026-54685
Published
Jul 20, 2026
Updated
Jul 20, 2026
Vendor
Graham Steffaniak
Product
FileBrowser Quantum
Classifications
CWE-208, CAPEC-541, CAPEC-580, CAPEC-462, T1087
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 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.

  1. Affected versionversion=< 1.3.2-beta

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Graham Steffaniak · FileBrowser Quantumversion=< 1.3.2-beta

Published CVSS scores

5.3GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-208Observable Timing Discrepancy
CAPEC-541Application Fingerprinting
CAPEC-580System Footprinting
CAPEC-462Cross-Domain Search Timing
T1087Account Discovery

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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