CVE-2023-2251 is a high-severity (CVSS 7.5) CWE-248 vulnerability in yaml. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for yaml — see the affected versions and patch details below.
Uncaught Exception in eemeli/yaml
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.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-2251.
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
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.
yamlnpmDescription
Uncaught Exception in GitHub repository eemeli/yaml starting at version 2.0.0-5 and prior to 2.2.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | yaml | ≥ 2.0.0-5&&< 2.2.2 | 2.2.2npm install yaml@2.2.2 |
Affected Products
yamlyaml_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 yaml, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update yaml to 2.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-2251 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.
Frequently Asked Questions
Is CVE-2023-2251 in your dependencies?
Find it across npm, including transitive dependencies.