# CVE-2026-107353: traverse: set() can write to built-in prototypes via an untrusted path

> Attackers can pollute built-in prototypes via untrusted paths in the traverse library, potentially leading to code execution or privilege escalation.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 Oct 2026
- **Updated:** 7 Oct 2026
- **Also known as:** AZL-107078, CLSA-2026-1792757149, CLSA-2026-1792757262, CLSA-2026-1792759996, CLSA-2026-1792760030, DEBIAN-CVE-2026-107353, GHSA-rj28-8w7x-jmqc, UBUNTU-CVE-2026-107353

## What is CVE-2026-107353?

CVE-2026-107353 is a medium-severity code injection vulnerability in ljharb traverse, published on 7 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

traverse (npm) versions 0.3.6 through 0.3.9, 0.4.0 through 0.4.6, 0.5.0 through 0.5.2, and 0.6.0 through 0.6.11 allow prototype pollution through set(). When the path passed to set() crosses a primitive value, the next path segment is resolved on that primitive's built-in prototype, so an application that passes an untrusted path to set() lets an attacker add or overwrite properties of String.prototype, Number.prototype, or Boolean.prototype using plain JSON data, for example traverse({ name: 'bob' }).set(['name', '__proto__', 'polluted'], 'yes'). Object.prototype was reachable only with a non-data path segment, such as an object whose toString returns a different value on each call, or through a Proxy that accepts an assignment without storing it. This is fixed in 0.3.10, 0.4.7, 0.5.3, and 0.6.12.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-107353?


## How do I fix CVE-2026-107353?

Upgrade to a fixed version.

## Is CVE-2026-107353 being exploited?

There is no known exploitation of CVE-2026-107353 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-107353 and fix it if it is affected.

What it is: CVE-2026-107353 is a medium-severity code injection vulnerability in ljharb traverse, published on 7 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-107353 in the wild and no public exploit code.

Affected product: ljharb traverse. 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-2026-107353/ (Markdown: https://insights.sbomify.com/CVE-2026-107353/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-107353
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-107353
- OSV: https://osv.dev/vulnerability/CVE-2026-107353

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-107353/
Summaries are generated and may contain mistakes; the official description above is the record.