CVE-2026-49356
LOWCVE-2026-49356 is a low-severity (CVSS 3.2) Path Traversal vulnerability in @babel/core. O3 Security confirms whether CVE-2026-49356 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Babel: Arbitrary File Read via sourceMappingURL Comment in @babel/core
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
@babel/corenpmDescription
Babel is a compiler for writing next generation JavaScript. Prior to 8.0.0-rc.6 and 7.29.6, @babel/core affected by an arbitrary file read via a sourceMappingURL comment. Using @babel/core to compile maliciously crafted code can allow an attacker to read any source map from the system that is running Babel, if the attacker controls the input source code, can read the output source code, and knows the path of the source map file that they want to read. This vulnerability is fixed in 8.0.0-rc.6 and 7.29.6.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @babel/core | ≥ 8.0.0-alpha.0&&< 8.0.0-rc.6 | 8.0.0-rc.6 |
| 📦npm | @babel/core | all versions | 7.29.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @babel/core. 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 @babel/core to 8.0.0-rc.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49356 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-2026-49356 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-2026-49356. 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-2026-49356 in your dependencies?
O3 detects CVE-2026-49356 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.