CVE-2026-31868 — parse-server
CVE-2026-31868 is a Cross-site Scripting (XSS) vulnerability in parse-server. A fix is available for parse-server — see the affected versions and patch details below.
Parse Server has Stored XSS via file upload of HTML-renderable file types
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 CVE-2026-31868.
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.
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.
parse-servernpmDescription
Impact
An attacker can upload a file with a file extension or content type that is not blocked by the default configuration of the Parse Server fileUpload.fileExtensions option. The file can contain malicious code, for example JavaScript in an SVG or XHTML file. When the file is accessed via its URL, the browser renders the file and executes the malicious code in the context of the Parse Server domain. This is a stored Cross-Site Scripting (XSS) vulnerability that can be exploited to steal session tokens, redirect users, or perform actions on behalf of other users.
Affected file extensions and content types include .svgz, .xht, .xml, .xsl, .xslt, and content types application/xhtml+xml and application/xslt+xml for extensionless uploads. Uploading of .html, .htm, .shtml, .xhtml, and .svg files was already blocked.
Patches
The fix adds the missing file extensions and content types to the default value of the fileUpload.fileExtensions server option.
Workarounds
Configure the fileUpload.fileExtensions server option to block the affected file extensions and content types.
References
- GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-v5hf-f4c3-m5rv
- Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.6.0-alpha.4
- Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.30
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | parse-server | ≥ 9.0.0-alpha.1&&< 9.6.0-alpha.4 | 9.6.0-alpha.4npm install parse-server@9.6.0-alpha.4 |
| 📦npm | parse-server | all versions | 8.6.30npm install parse-server@8.6.30 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for parse-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update parse-server to 9.6.0-alpha.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-31868 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-2026-31868 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-31868. 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-2026-31868 in your dependencies?
O3 Security finds CVE-2026-31868 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.