CVE-2017-18349 is a critical-severity (CVSS 9.8) Improper Input Validation vulnerability in com.alibaba:fastjson. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for com.alibaba:fastjson — see the affected versions and patch details below.
Improper Input Validation in alilibaba:fastjson
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
com.alibaba:fastjson☕ro.pippo:pippo-fastjsonReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
parseObject in Fastjson before 1.2.25, as used in FastjsonEngine in Pippo 1.11.0 and other products, allows remote attackers to execute arbitrary code via a crafted JSON request, as demonstrated by a crafted rmi:// URI in the dataSourceName field of HTTP POST data to the Pippo /json URI, which is mishandled in AjaxApplication.java.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.alibaba:fastjson | all versions | 1.2.31com.alibaba:fastjson:1.2.31 |
| ☕Maven | ro.pippo:pippo-fastjson | all versions | 1.12.0ro.pippo:pippo-fastjson:1.12.0 |
Affected Products
fastjsonalibabapippopippoResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.alibaba:fastjson, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.alibaba:fastjson to 1.2.31 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-18349 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 to detect CVE-2017-18349
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2017-18349 -u https://target- Template
- Fastjson Insecure Deserialization - Remote Code Execution
- Severity
- critical
- Impact
- Successful exploitation allows complete system compromise through remote code execution, enabling attackers to execute arbitrary commands, access sensitive data, and establish persistent backdoors on the target system.
- Remediation
- Update Fastjson to version 1.2.25 or later which includes security patches for this vulnerability.Disable autotype functionality by setting `fastjson.parser.autoTypeSupport=false`.Implement strict whitelist filtering for `@type` annotations, validate and sanitize all JSON input.Use Web Application Firewalls (WAF) to filter malicious requests, and regularly audit dependencies for known vulnerabilities. Consider migrating to safer JSON parsing libraries like Jackson with secure configurations.
Template by ProjectDiscovery nuclei-templates (night), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2017-18349 in your dependencies?
Find it across Maven, including transitive dependencies.