---
title: "undici - Authentication Bypass"
description: "undici 4.0.0 to 6.29.0, 7.0.0 to 7.30.0, and 8.0.0 to 8.12.1 contain a broken authentication caused by JSON-based deep cloning dropping custom checkServerIdentity callbacks in TLS options, letting attackers bypass custom TLS certificate verification, exploit requires passing a function-valued tls option."
url: https://panop.io/threat-heartbeat/CVE-2026-109383/
---

# CVE-2026-109383 undici - Authentication Bypass

undici 4.0.0 to 6.29.0, 7.0.0 to 7.30.0, and 8.0.0 to 8.12.1 contain a broken authentication caused by JSON-based deep cloning dropping custom checkServerIdentity callbacks in TLS options, letting attackers bypass custom TLS certificate verification, exploit requires passing a function-valued tls option.

CVSS base score 7.4 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-109383)

## Details

Type

Broken Authentication

Impact

Man In The Middle

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Published

15 October 2026

Updated

16 October 2026

Weakness

[CWE-295](https://cwe.mitre.org/data/definitions/295.html)

## Vendor fix

Upgrade to undici 6.29.1, 7.30.1, 8.12.2 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-109383](https://nvd.nist.gov/vuln/detail/CVE-2026-109383)
- [https://github.com/nodejs/undici/security/advisories/GHSA-2m5v-pch6-74hx](https://github.com/nodejs/undici/security/advisories/GHSA-2m5v-pch6-74hx)
- [https://cna.openjsf.org/security-advisories.html](https://cna.openjsf.org/security-advisories.html)

[← All CVEs](https://panop.io/threat-heartbeat/)

## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

[Book a demo](https://panop.io/demo)