How severe is CVE-2026-49356?

CVE-2026-49356 has a CVSS score of 3.2/10, rated LOW. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-49356?

CVE-2026-49356 affects the following packages: @babel/core (npm), @babel/core (npm). Ecosystems affected: npm.

How do I fix CVE-2026-49356?

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.

How do I detect CVE-2026-49356 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @babel/core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-49356 if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Is CVE-2026-49356 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-49356 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-49356?

CVE-2026-49356 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 4th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-49356?

CVE-2026-49356 is classified as Path Traversal (CWE-22), Information Exposure (CWE-200). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-49356 published, and has it been updated?

CVE-2026-49356 was published on June 22, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

LOW severity

CVE-2026-49356 — @babel/core

LOW

CVE-2026-49356 is a low-severity (CVSS 3.2) Path Traversal vulnerability in @babel/core. A fix is available for @babel/core — see the affected versions and patch details below.

Babel: Arbitrary File Read via sourceMappingURL Comment in @babel/core

Also known asGHSA-4x5r-pxfx-6jf8

Published

Jun 22, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 1, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-49356.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs4th percentile — riskier than 4% of all scored CVEsHighest risk

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

2 pkgs affected

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.

24Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

@babel/corenpm

245.6Mdownloads / week

Description

Impact

Using @babel/core to compile maliciously crafted code can allow ab attacker to read any source map from the system that is running Babel, if these conditions are all true:

the attacker controls the input source code
the attacker can read the output source code
the attacker knows the path of the source map file that they want to read

Users that only compile trusted code are not impacted.

Patches

The vulnerability has been fixed in @babel/[email protected] and @babel/[email protected].

Workarounds

Callers can mitigate the issue without upgrading by setting inputSourceMap: false in their Babel options.

Callers can also manually extract the #sourceMappingURL comment from the input source code, validate whether the source map that it links to is allowed to be read, and if it is pass an object to inputSourceMap (passing false when it's not).

Credits

Thanks Teodor-Cristian Radoi for reporting the vulnerability.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@babel/core`	≥ 8.0.0-alpha.0&&< 8.0.0-rc.6	8.0.0-rc.6`npm install @babel/core@8.0.0-rc.6`
📦npm	`@babel/core`	all versions	7.29.6`npm install @babel/core@7.29.6`

Affected Products

1 product · 29 configurations

Application

babelbabel

< 7.29.6

1 version

8.0.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @babel/core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatLow

Red Hat rates this issue as having Low impact for Red Hat AI products. @babel/core is bundled only in build-time or developer UI tooling (dashboard, model registry, MLflow) and the arbitrary file read requires local access and attacker-controlled source map processing that is not exposed in normal production use.

Workaround published by Red Hat

Do not process untrusted source maps with @babel/core in production services. Restrict access to developer UI components.

Source: Red Hat security advisory for CVE-2026-49356 (CC BY 4.0)

Frequently Asked Questions

## Impact Using `@babel/core` to compile maliciously crafted code can allow ab attacker to read any source map from the system that is running Babel, if these conditions are _all_ true: - the attacker controls the input source code - the attacker can read the output source code - the attacker knows the path of the source map file that they want to read **Users that only compile trusted code are not impacted.** ## Patches The vulnerability has been fixed in `@babel/[email protected]` and `@babel/[email protected]`. ## Workarounds Callers can mitigate the issue without upgrading by setting [`input