CVE-2017-18640 — snakeyaml
HIGHCVE-2017-18640 is a high-severity (CVSS 7.5) CWE-776 vulnerability in org.yaml:snakeyaml. 2 public exploit references exist, so weaponization risk is real. A fix is available for org.yaml:snakeyaml — see the affected versions and patch details below.
SnakeYAML Entity Expansion during load operation
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2017-18640 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
org.yaml:snakeyamlReal-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
The Alias feature in SnakeYAML before 1.26 allows entity expansion during a load operation, a related issue to CVE-2003-1564.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.yaml:snakeyaml | all versions | 1.26org.yaml:snakeyaml:1.26 |
Affected Products
fedorafedoraprojectpeoplesoft enterprise pt peopletoolsoraclequarkusquarkussnakeyamlsnakeyaml_projectResearch 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 org.yaml:snakeyaml, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.yaml:snakeyaml to 1.26 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-18640 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.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat AMQ Streams 1.8.0 | prometheus-jmx-exporter | RHSA-2021:3225 |
| Red Hat build of Quarkus 1.3.4 | snakeyaml | RHSA-2020:2603 |
| Red Hat Enterprise Linux 8 | prometheus-jmx-exporter-0:0.12.0-6.el8 | RHSA-2020:4807 |
| Red Hat Fuse 7.9 | prometheus-jmx-exporter | RHSA-2021:3140 |
Frequently Asked Questions
Is CVE-2017-18640 in your dependencies?
Find it across Maven, including transitive dependencies.