# CVE-2026-39245: Path traversal in n/a

> An attacker can exploit flawed path validation to write arbitrary files outside the intended directory, potentially leading to code execution.

- **Severity:** Medium 6.2 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Jul 2026
- **Updated:** 10 Jul 2026
- **Also known as:** GHSA-qcj4-cj8p-fhf4

## What is CVE-2026-39245?

CVE-2026-39245 is a medium-severity path traversal vulnerability in n/a, published on 9 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

decompress before 4.2.2 contains an improper path containment check that enables directory traversal and arbitrary file write. The safeMakeDir function (index.js line 29) and the extraction path validation (index.js line 106) use String.indexOf() to verify the resolved path is within the output directory: realDestinationDir.indexOf(realOutputPath) !== 0. This check is flawed because it does not enforce a path separator boundary. For example, "/tmp/app_config".indexOf("/tmp/app") returns 0, incorrectly passing the check even though /tmp/app_config is outside /tmp/app. Combined with the unvalidated symlink creation in the same package, an attacker can write arbitrary files to directories adjacent to the extraction target. This is a bypass of the fix for CVE-2020-12265. The correct check requires appending a path separator: realParentPath.indexOf(realOutputPath + path.sep) !== 0.

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

## Which versions are affected by CVE-2026-39245?

It affects 1 product.


Products: Decompress Project Decompress.

## How do I fix CVE-2026-39245?

Upgrade to a fixed version.

## Is CVE-2026-39245 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39245 exists.

## Other vulnerabilities in n/a

- [CVE-2020-12265](https://insights.sbomify.com/CVE-2020-12265/): Path Traversal in decompress (critical 9.8)
- [CVE-2026-39246](https://insights.sbomify.com/CVE-2026-39246/): Path traversal in n/a (high 7.5)
- [CVE-2026-39243](https://insights.sbomify.com/CVE-2026-39243/): decompress allows arbitrary hardlink creation during archive extraction (medium 5.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39245 and fix it if it is affected.

What it is: CVE-2026-39245 is a medium-severity path traversal vulnerability in n/a, published on 9 Jul 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-2026-39245 exists.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-39245/ (Markdown: https://insights.sbomify.com/CVE-2026-39245/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39245
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39245
- OSV: https://osv.dev/vulnerability/CVE-2026-39245

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39245/
Summaries are generated and may contain mistakes; the official description above is the record.