CVE-2026-27837
MEDIUMCVE-2026-27837 is a medium-severity (CVSS 6.3) CWE-1321 vulnerability in dottie. O3 Security confirms whether CVE-2026-27837 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Dottie vulnerable to prototype pollution bypass via non-first path segments in set() and transform()
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
dottienpmDescription
Dottie provides nested object access and manipulation in JavaScript. Versions 2.0.4 through 2.0.6 contain an incomplete fix for CVE-2023-26132. The prototype pollution guard introduced in commit 7d3aee1 only validates the first segment of a dot-separated path, allowing an attacker to bypass the protection by placing __proto__ at any position other than the first. Both dottie.set() and dottie.transform() are affected. Version 2.0.7 contains an updated fix to address the residual vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | dottie | ≥ 2.0.4&&< 2.0.7 | 2.0.7 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for dottie. 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 dottie to 2.0.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-27837 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-2026-27837 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-2026-27837. 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-2026-27837 in your dependencies?
O3 detects CVE-2026-27837 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.