CVE-2026-48777Public exploitNetwork attack vectorHinoki check available

Arbitrary file read and write via pre-sanitization join

Published Jun 16, 2026 · Updated Jun 16, 2026

Path traversal in FileBrowser Quantum before 1.3.3-stable and 1.4.0-beta through 1.4.1-beta allows remote attackers to read and write files. The publicPatchHandler joins untrusted fromPath and toPath values to d.share.Path before sanitization, so path normalization removes traversal segments before resourcePatchHandler checks them. Possession of a public share link with AllowModify enabled is sufficient to read or overwrite files within the share owner's source root, but not files beyond that root.

CVSS severity9.3
Critical
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Path traversal in FileBrowser Quantum before 1.3.3-stable and 1.4.0-beta through 1.4.1-beta allows remote attackers to read and write files. The publicPatchHandler joins untrusted fromPath and toPath values to d.share.Path before sanitization, so path normalization removes traversal segments before resourcePatchHandler checks them. Possession of a public share link with AllowModify enabled is sufficient to read or overwrite files within the share owner's source root, but not files beyond that root.

The record

CVE
CVE-2026-48777
Published
Jun 16, 2026
Updated
Jun 16, 2026
Vendor
Graham Steffaniak
Product
FileBrowser Quantum
Classifications
CWE-22, T1565.001, T1005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 16, 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=< 1.3.3-stable
  2. Affected versionversion=>= 1.4.0-beta, < 1.4.2-beta

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Graham Steffaniak · FileBrowser Quantumversion=< 1.3.3-stable; version=>= 1.4.0-beta, < 1.4.2-beta

Published CVSS scores

9.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA: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-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1565.001Stored Data Manipulation
T1005Data from Local System

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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