CVE-2026-34523 — sillytavern
MEDIUMCVE-2026-34523 is a medium-severity (CVSS 5.3) Path Traversal vulnerability in sillytavern. A fix is available for sillytavern — see the affected versions and patch details below.
SillyTavern: Path traversal allows file existence oracle
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34523.
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
CVE-2026-34523 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 377,636 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
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
sillytavernnpmDescription
Summary
A path traversal vulnerability in the static file route handler allows any unauthenticated user to determine whether files exist anywhere on the server's filesystem. By sending percent-encoded ../ sequences (%2E%2E%2F) in requests to static file routes, an attacker can check for the existence of files (404 if it doesn't exist, 403 means it exists).
Details
The vulnerability is in createRouteHandler (src/users.js:947–963), which backs all user-data static file routes:
function createRouteHandler(directoryFn) {
return async (req, res) => {
const directory = directoryFn(req);
const filePath = decodeURIComponent(req.params[0]);
const exists = fs.existsSync(path.join(directory, filePath)); // no boundary check here
if (!exists) {
return res.sendStatus(404);
}
return res.sendFile(filePath, { root: directory });
};
}
req.params[0] contains the raw (percent-encoded) wildcard from the URL. After decodeURIComponent, a request path like /characters/%2E%2E%2F%2E%2E%2FUsers/kirakira decodes to ../../Users/kirakira, and path.join resolves it outside the intended directory. res.sendFile correctly blocks the file from being served (the send module's root check returns 403), but fs.existsSync had already run, and the 403/404 distinction reveals the result.
Affected routes (they all use the same handler, so they're all affected):
/characters/*/user/files/*/assets/*/user/images/*/backgrounds/*/User%20Avatars/*
PoC
curl -o /dev/null -s -w "%{http_code}\n" "http://localhost:8000/characters/%2E%2E%2F%2E%2E%2F%2E%2E%2F%2E%2E%2F%2E%2E%2F%2E%2E%2F%2E%2E%2FUsers/kirakira/something"
Impact
While file contents cannot be read (the send module blocks actual delivery), anyone who can reach the SillyTavern HTTP port can check the existence of files on the host filesystem.
Resolution
The issue was addressed in version 1.17.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | sillytavern | all versions | 1.17.0npm install sillytavern@1.17.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sillytavern, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update sillytavern to 1.17.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34523 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-34523 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-34523. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-34523 in your dependencies?
O3 Security finds CVE-2026-34523 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.