How severe is GHSA-r633-fcgp-m532?

GHSA-r633-fcgp-m532 has a CVSS score of 8.9/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-r633-fcgp-m532?

GHSA-r633-fcgp-m532 affects the following packages: github.com/gtsteffaniak/filebrowser (Go). Ecosystems affected: Go.

How do I fix GHSA-r633-fcgp-m532?

Update github.com/gtsteffaniak/filebrowser to 0.0.0-20260307130210-09713b32a5f6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r633-fcgp-m532 is resolved across your whole dependency graph.

How do I detect GHSA-r633-fcgp-m532 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gtsteffaniak/filebrowser. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-r633-fcgp-m532 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-r633-fcgp-m532?

O3 pinpoints whether GHSA-r633-fcgp-m532 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-r633-fcgp-m532 actively exploited in the wild?

No public exploit code has been indexed for GHSA-r633-fcgp-m532 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-r633-fcgp-m532?

GHSA-r633-fcgp-m532 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 26th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-r633-fcgp-m532?

GHSA-r633-fcgp-m532 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-r633-fcgp-m532 published, and has it been updated?

GHSA-r633-fcgp-m532 was published on March 9, 2026 and was last updated on March 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

GHSA-r633-fcgp-m532

HIGH

FileBrowser Quantum: Stored XSS in public share page via unsanitized share metadata (text/template misuse)

Also known asCVE-2026-30934GO-2026-4660

Published

Mar 9, 2026

Updated

Mar 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk26th percentile+0.30%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🐹github.com/gtsteffaniak/filebrowser

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

Stored XSS is possible via share metadata fields (e.g., title, description) that are rendered into HTML for /public/share/<hash> without context-aware escaping. The server uses text/template instead of html/template, allowing injected scripts to execute when victims visit the share URL.

Details

The server renders public/index.html using text/template and injects user-controlled share fields (title/description/etc.) into HTML contexts. text/template does not perform HTML contextual escaping like html/template. Because share metadata is persistent, the payload becomes stored and executes whenever a victim opens the affected share page.

Relevant code paths:

backend/http/static.go (template rendering and share metadata assignment)
backend/http/httpRouter.go (template initialization)
frontend/public/index.html (insertion points for title/description and related fields)

PoC

Login as a user with share creation permission.
Create a share (POST /api/share) with malicious metadata:
- title = </title><script>alert("xss")</script><title>
Open the resulting /public/share/<hash> URL in a browser.
Expected: Payload is safely escaped and displayed as text.
Actual: JavaScript executes in victim's browser (stored XSS).

Tested on Docker image: gtstef/filebrowser:stable (version v1.2.1-stable).

Impact

Arbitrary script execution in application origin.
Potential account/session compromise, CSRF-like action execution, data exfiltration from authenticated contexts.
Affects anyone (including unauthenticated visitors) opening the malicious share URL.
The XSS is stored and persistent — no social engineering beyond sharing the link is required.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/gtsteffaniak/filebrowser`	all versions	0.0.0-20260307130210-09713b32a5f6

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gtsteffaniak/filebrowser. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/gtsteffaniak/filebrowser to 0.0.0-20260307130210-09713b32a5f6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r633-fcgp-m532 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-r633-fcgp-m532 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-r633-fcgp-m532. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary Stored XSS is possible via share metadata fields (e.g., `title`, `description`) that are rendered into HTML for `/public/share/<hash>` without context-aware escaping. The server uses `text/template` instead of `html/template`, allowing injected scripts to execute when victims visit the share URL. ## Details The server renders `public/index.html` using `text/template` and injects user-controlled share fields (title/description/etc.) into HTML contexts. `text/template` does not perform HTML contextual escaping like `html/template`. Because share metadata is persistent, the payload be

O3 Security · Impact-Aware SCA

Is GHSA-r633-fcgp-m532 in your dependencies?

O3 detects GHSA-r633-fcgp-m532 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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