# CVE-2026-49406: Deno: BYONM module resolution allows `package.json` main path traversal to bypass `--allow-read` restrictions

> A path traversal in Deno's BYONM mode allows malicious packages to bypass read restrictions and access arbitrary files on disk.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Jun 2026
- **Updated:** 23 Jun 2026
- **Also known as:** GHSA-968w-xfqw-vp9q, JLSEC-2026-657

## What is CVE-2026-49406?

CVE-2026-49406 is a medium-severity path traversal vulnerability in denoland deno, published on 23 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.12, when Deno was run in BYONM mode (nodeModulesDir: "manual"), the module resolver did not validate that a package's resolved entrypoint stayed within its node_modules/<pkg>/ directory. A malicious package.json whose main field contained .. segments was able to resolve to an arbitrary path on disk, and the resolver then read that file without consulting the --allow-read allowlist. This let a require("evil-pkg") call return the contents of a file that a direct Deno.readTextFileSync(...) call would have been blocked from reading. This vulnerability is fixed in 2.7.12.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-49406?

2 open source packages ship an affected version, including deno. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `deno` | crates.io | All versions | 2.7.12 |
| `deno` | crates.io | All versions | 2.7.12 |

Products: Deno Deno.

## How do I fix CVE-2026-49406?

Upgrade deno to 2.7.12 or later.

## Is CVE-2026-49406 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49406 exists.

## Other vulnerabilities in denoland deno

- [CVE-2023-28445](https://insights.sbomify.com/CVE-2023-28445/): Deno improperly handles resizable ArrayBuffer (critical 10.0)
- [CVE-2022-24783](https://insights.sbomify.com/CVE-2022-24783/): Sandbox bypass leading to arbitrary code execution in Deno (critical 10.0)
- [CVE-2021-32619](https://insights.sbomify.com/CVE-2021-32619/): Static imports inside dynamically imported modules do not adhere to permission checks (critical 9.8)
- [CVE-2026-22863](https://insights.sbomify.com/CVE-2026-22863/): Deno node:crypto doesn't finalize cipher (critical 9.2)
- [CVE-2024-27936](https://insights.sbomify.com/CVE-2024-27936/): Deno interactive permission prompt spoofing via improper ANSI stripping (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49406 and fix it if it is affected.

What it is: CVE-2026-49406 is a medium-severity path traversal vulnerability in denoland deno, published on 23 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49406 exists.

Affected packages and fixed versions:
- deno (crates.io): affected all versions; fixed in 2.7.12
- deno (crates.io): affected all versions; fixed in 2.7.12

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-49406/ (Markdown: https://insights.sbomify.com/CVE-2026-49406/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49406
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49406
- OSV: https://osv.dev/vulnerability/CVE-2026-49406

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49406/
Summaries are generated and may contain mistakes; the official description above is the record.