How severe is CVE-2017-18640?

CVE-2017-18640 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2017-18640?

CVE-2017-18640 affects the following packages: org.yaml:snakeyaml (Maven). Ecosystems affected: Maven.

How do I fix CVE-2017-18640?

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.

How do I detect CVE-2017-18640 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.yaml:snakeyaml. 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.

How do I mitigate CVE-2017-18640 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2017-18640?

O3 pinpoints whether CVE-2017-18640 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2017-18640 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2017-18640, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What type of vulnerability is CVE-2017-18640?

CVE-2017-18640 is classified as CWE-776 (CWE-776). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2017-18640 published, and has it been updated?

CVE-2017-18640 was published on December 12, 2019 and was last updated on July 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

CVE-2017-18640

HIGH

SnakeYAML Entity Expansion during load operation

Also known asGHSA-rvwf-54qp-4r6v

Published

Dec 12, 2019

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

2 known

Blast Radius

1 pkg affected

☕org.yaml:snakeyaml

Real-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

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.yaml:snakeyaml`	all versions	1.26

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

The Alias feature in SnakeYAML before 1.26 allows entity expansion durin…

bitbucket.orgNVDJun 2021

The Alias feature in SnakeYAML before 1.26 allows entity expansion durin…

bitbucket.orgNVDFeb 2023

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.yaml:snakeyaml. 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 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.
How O3 protects you
O3 pinpoints whether CVE-2017-18640 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-2017-18640. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

The Alias feature in SnakeYAML before 1.26 allows entity expansion during a load operation, a related issue to CVE-2003-1564.

O3 Security · Impact-Aware SCA

Is CVE-2017-18640 in your dependencies?

O3 detects CVE-2017-18640 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works