CVE-2026-44542: FileBrowser Public Share DELETE API Path Traversal Allows Unauthenticated Arbitrary File Deletion

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.6%, percentile 48: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 48% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes github.com/gtsteffaniak/filebrowser (Go) < 0.0.0-20260501183844-112740bdd41d, fixed in 0.0.0-20260501183844-112740bdd41d. Check your lockfile, including transitive dependencies.

What it is

FileBrowser Quantum is a free, self-hosted, web-based file manager. Prior to 1.3.1-stable and 1.3.9-beta, attacker-controlled path input is joined with a trusted base path prior to sanitization, allowing traversal sequences (e.g., ../) to escape the intended shared directory. As a result, an unauthenticated attacker possessing a valid public share hash with delete permissions enabled can delete arbitrary files outside the shared directory within the share owner’s configured storage scope. This affects public/api/resources and public/api/resources/bulk. This vulnerability is fixed in 1.3.1-stable and 1.3.9-beta.

From the GitHub advisory

Summary

Attacker-controlled path input is joined with a trusted base path prior to sanitization, allowing traversal sequences (e.g., ../) to escape the intended shared directory. As a result, an unauthenticated attacker possessing a valid public share hash with delete permissions enabled can delete arbitrary files outside the shared directory within the share owner’s configured storage scope.

Affected Components

Two distinct vulnerable code paths:

1. Stable versions (e.g., gtstef/filebrowser:stable) DELETE /public/api/resources?hash= &path=../victim Root cause: middleware.go:111 Issue: path query parameter is joined before SanitizeUserPath() 2. Development / HEAD (e.g., commit eabdfd9) DELETE /public/api/resources/bulk?hash= Body: [{"path":"../victim"}] Root cause: resource.go:274 Issue: item.Path is joined before SanitizeUserPath()

Weakness type: CWE-22.

Product: github.com/gtsteffaniak/filebrowser (Go) · Assigned by: GitHub_M · Published: 2026-05-14

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable yes, technical impact partial.
• FIRST EPSS (model of 2026-10-21): 0.60% probability of exploitation activity in the next 30 days; percentile 48.

Timeline

• 2026-05-07 — GitHub-reviewed advisory GHSA-fwj3-42wh-8673 published (critical)
• 2026-05-14 — CVE record published by GitHub_M
• 2026-05-15 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-fwj3-42wh-8673 github.com
2. CVE.org record CVE-2026-44542 cve.org
3. NVD entry CVE-2026-44542 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com

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