# CVE-2026-44966: Velocity.js: Prototype Pollution in #set path assignment

> Attackers can achieve remote code execution or denial of service via prototype pollution in Velocity.js template processing.

- **Severity:** High 8.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 May 2026
- **Updated:** 1 Jun 2026
- **Also known as:** GHSA-j658-c2gf-x6pq

## What is CVE-2026-44966?

CVE-2026-44966 is a high-severity code injection vulnerability in shepherdwind velocity.js, published on 26 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Velocity.js is a JavaScript implementation of the Apache Velocity template engine. In 2.1.5 and earlier, a prototype pollution vulnerability was discovered in velocityjs. This issue occurs during the processing of #set directives in Velocity templates. If an application renders a template controlled by an attacker, it is possible to modify Object.prototype, potentially leading to Denial of Service (DoS) or Remote Code Execution (RCE) depending on the server environment.

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

## Which versions are affected by CVE-2026-44966?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `velocityjs` | npm | All versions to 2.1.5 | None |
| `velocityjs` | npm | All versions to 2.1.5 | None |

Products: Shepherdwind Velocity.js.

## How do I fix CVE-2026-44966?

No fix has been published for CVE-2026-44966 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-44966 being exploited?

There is no known exploitation of CVE-2026-44966 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44966 and fix it if it is affected.

What it is: CVE-2026-44966 is a high-severity code injection vulnerability in shepherdwind velocity.js, published on 26 May 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-2026-44966 in the wild and no public exploit code.

Affected packages and fixed versions:
- velocityjs (npm): affected all versions up to 2.1.5; no fix listed
- velocityjs (npm): affected all versions up to 2.1.5; no fix listed

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-2026-44966/ (Markdown: https://insights.sbomify.com/CVE-2026-44966/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44966
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44966
- OSV: https://osv.dev/vulnerability/CVE-2026-44966

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44966/
Summaries are generated and may contain mistakes; the official description above is the record.