# CVE-2026-34752: Haraka affected by DoS via `__proto__` email header

> An attacker can crash the Haraka mail server worker process by sending an email with a specific header, requiring a patch to restore service.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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:** 2 Apr 2026
- **Updated:** 3 Apr 2026
- **Also known as:** GHSA-xph3-r2jf-4vp3

## What is CVE-2026-34752?

CVE-2026-34752 is a high-severity denial of service vulnerability in Haraka, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Haraka is a Node.js mail server. Prior to version 3.1.4, sending an email with __proto__: as a header name crashes the Haraka worker process. This issue has been patched in version 3.1.4.

Weakness: CWE-248 (Uncaught Exception)

## Which versions are affected by CVE-2026-34752?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `Haraka` | npm | All versions | 3.1.4 |
| `Haraka` | npm | All versions | 3.1.4 |

Products: Haraka Project Haraka.

## How do I fix CVE-2026-34752?

Upgrade Haraka to 3.1.4 or later.

## Is CVE-2026-34752 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34752 exists.

## Other vulnerabilities in Haraka

- [CVE-2016-1000282](https://insights.sbomify.com/CVE-2016-1000282/): Critical severity vulnerability that affects Haraka (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34752 and fix it if it is affected.

What it is: CVE-2026-34752 is a high-severity denial of service vulnerability in Haraka, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34752 exists.

Affected packages and fixed versions:
- Haraka (npm): affected all versions; fixed in 3.1.4
- Haraka (npm): affected all versions; fixed in 3.1.4

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-2026-34752/ (Markdown: https://insights.sbomify.com/CVE-2026-34752/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34752
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34752
- OSV: https://osv.dev/vulnerability/CVE-2026-34752

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34752/
Summaries are generated and may contain mistakes; the official description above is the record.