GHSA-85jm-cwp2-mvpv
MEDIUMGHSA-85jm-cwp2-mvpv is a medium-severity (CVSS 5.3) Path Traversal vulnerability in CefSharp.Common. O3 Security confirms whether GHSA-85jm-cwp2-mvpv is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
CefSharp.Common: `FolderSchemeHandlerFactory` path boundary check can expose files outside the configured root folder
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-85jm-cwp2-mvpv.
EPSS Exploitation Probability
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.
How urgent is this, really
GHSA-85jm-cwp2-mvpv plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
CefSharp.CommonReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Summary
FolderSchemeHandlerFactory was intended to restrict served files to a configured rootFolder, but its path validation used a raw string prefix check. A request could escape to a sibling directory whose full path starts with the root folder path, allowing files outside the configured root to be served.
Details
In affected versions, FolderSchemeHandlerFactory canonicalized rootFolder, decoded the request path, combined it with the root, and then allowed the file when:
filePath.StartsWith(rootFolder, StringComparison.OrdinalIgnoreCase)
This does not enforce a directory boundary. For example, /tmp/app/www2/secret.txt starts with /tmp/app/www, but www2 is a sibling of www, not a child. The same issue applies on Windows, for example C:\app\www2\secret.txt starts with C:\app\www.
The affected code was reviewed at commit b5fef3bb4bc58798c95170078c41de92cfe9066e, assembly version 147.0.100.
PoC
Set rootFolder to a directory named www and create a sibling directory named www2:
<temp>/www/index.html
<temp>/www2/secret.txt
Register FolderSchemeHandlerFactory for <temp>/www, then request:
https://folderschemehandlerfactory.test/..%2fwww2/secret.txt
The request path is URL-decoded to ../www2/secret.txt, combined with <temp>/www, and canonicalized to:
<temp>/www2/secret.txt
Because <temp>/www2/secret.txt starts with <temp>/www as a string prefix, the affected check passes and secret.txt is served from outside rootFolder.
Expected vulnerable result: HTTP 200 with the contents of <temp>/www2/secret.txt.
Expected fixed result: 404 or equivalent not-found response because the resolved file is outside rootFolder.
Impact
Applications using FolderSchemeHandlerFactory for a custom scheme or registered HTTP/HTTPS scheme may expose local files outside the intended served directory. This is most relevant when sensitive sibling directories share the root path prefix, such as www/www2, public/public_backup, or static/static-secrets.
An attacker must be able to cause the embedded browser to request URLs handled by the affected scheme registration.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | CefSharp.Common | all versions | 148.0.90 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for CefSharp.Common. 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 CefSharp.Common to 148.0.90 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-85jm-cwp2-mvpv 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-85jm-cwp2-mvpv 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-85jm-cwp2-mvpv. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-85jm-cwp2-mvpv in your dependencies?
O3 detects GHSA-85jm-cwp2-mvpv across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.