CVE-2026-48777

CRITICALPre-NVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 63% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
9.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

FileBrowser Quantum is a free, self-hosted, web-based file manager. Versions prior to 1.3.2-stable, 1.4.0-beta and 1.4.1-beta are vulnerable to Path Traversal through the publicPatchHandler in backend/http/public.go which joins user-controlled fromPath and toPath body fields with the trusted d.share.Path BEFORE the downstream sanitizer runs. Because filepath.Join collapses .. segments during the join, the sanitizer in resourcePatchHandler never sees the traversal and the move/copy/rename operates on a path outside the shared directory. The same root-cause pattern was patched for the bulk DELETE endpoint as CVE-2026-44542 (GHSA-fwj3-42wh-8673), but the PATCH handler with the identical pattern was not updated. A public share link with AllowModify=true is sufficient to exploit this. Anyone holding such a link can move, copy, or rename arbitrary files within the share owner's source root. This issue has been fixed in versions 1.3.3-stable and 1.4.2-beta.

CVSS v3
9.3
EG Score
9.3CRITICALmedium confidence
EG Risk
47
EG Risk 47/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity93% × 45%
Exploitation0% × 40%
Automatability30% × 15%
EPSS PROB
0.5%
EPSS %ILE
42nd
KEV
Not listed

Published

May 22, 2026

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Sep 23, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_release.
githubMentions a patch (unverified)🟡 PoC Available

Path traversal in public share PATCH allows file ops outside shared directory · Advisory · gtsteffaniak/filebrowser · GitHub

https://github.com/gtsteffaniak/filebrowser/security/advisories/GHSA-qqqm-5547-774x
github_release Patch Available

v1.4.2-beta

Patch available: gtsteffaniak/filebrowser v1.4.2-beta (pre-release)

https://github.com/gtsteffaniak/filebrowser/releases/tag/v1.4.2-beta
github_release Patch Available

v1.3.3-stable

Patch available: gtsteffaniak/filebrowser v1.3.3-stable

https://github.com/gtsteffaniak/filebrowser/releases/tag/v1.3.3-stable

Vendor Advisories for CVE-2026-48777(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFix by version rangeDependents
github.com/gtsteffaniak/filebrowser/backend—
  • every version up to 0.0.0-20260518193514-28e9b81e438e: fixed in 0.0.0-20260518193514-28e9b81e438e
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 22× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 135 total refreshes for this CVE.

  1. 2026-10-07 23:48 UTCEPSS rescore
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  19. 2026-09-11 17:23 UTCOSV refresh
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  1. 2026-09-02 14:12 UTCEPSS rescore
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  45. 2026-08-03 16:47 UTCEG score recompute
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  75. 2026-07-09 19:10 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-48777?
CVE-2026-48777 is a critical vulnerability published on May 22, 2026. FileBrowser Quantum is a free, self-hosted, web-based file manager. Versions prior to 1.3.2-stable, 1.4.0-beta and 1.4.1-beta are vulnerable to Path Traversal through the publicPatchHandler in backend/http/public.go which joins user-controlled fromPath and toPath body fields with the trusted…
When was CVE-2026-48777 disclosed?
CVE-2026-48777 was first published on May 22, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-48777 actively exploited?
CVE-2026-48777 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (42nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-48777?
CVE-2026-48777 has a CVSS base score of 9.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-48777?
A fix for CVE-2026-48777 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-48777 are linked in the Vendor Advisories panel on this page.

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