CVE-2026-49356 Babel: Arbitrary File Read via sourceMappingURL Comment in @babel/core
Attackers can read arbitrary source map files from the system by crafting malicious input code processed by Babel, exposing sensitive source code.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-49356?
CVE-2026-49356 is a low-severity path traversal vulnerability in babel, published on 22 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-49356?
4 open source packages ship an affected version, including @babel/core. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
@babel/core npm | All versions | 7.29.6 |
@babel/core npm | All versions | 7.29.6 |
@babel/core npm | From 8.0.0-alpha.0 | 8.0.0-rc.6 |
@babel/core npm | From 8.0.0-alpha.0 | 8.0.0-rc.6 |
Products include Babel Babel.
How do I fix CVE-2026-49356?
Upgrade @babel/core to a fixed version for your release line: 7.29.6 or 8.0.0-rc.6.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-49356 being exploited?
There is no known exploitation of CVE-2026-49356 in the wild and no public exploit code.
Other vulnerabilities in babel
Sources
Also known as CLEANSTART-2026-SW35830, CLSA-2026-1784596301, CLSA-2026-1790109160, CLSA-2026-1790181820, CLSA-2026-1790212818, CLSA-2026-1792160971 and 308 more.