---
id: CVE-2026-93601
title: >-
  rustls-webpki (the Rust webpki fork used by rustls) versions >= 0.101.0 and
  prior to 0.103.12 and 0.104.0-alpha.6 incorrectly accepted permitted-subtree
  DNS name constraints for certificates asserting a wildcard name
summary: >-
  rustls-webpki (the Rust webpki fork used by rustls) versions >= 0.101.0 and
  prior to 0.103.12 and 0.104.0-alpha.6 incorrectly accepted permitted-subtree
  DNS name constraints for certificates asserting a wildcard name. For example,
  a name…
severity: low
cvss: 2.2
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-295
  - CWE-1289
vendor: rustls
product: webpki
affected:
  - webpki >= 0.101.0 < 0.103.12
  - webpki >= 0.104.0-alpha.1 < 0.104.0-alpha.6
patched:
  - rustls-webpki 0.104.0-alpha.6
published: '2026-09-18'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T20:25:55.870'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93601'
references:
  - url: 'https://github.com/rustls/webpki/security/advisories/GHSA-xgp8-3hg3-c2mh'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/rustls-webpki-0.101.0-before-0.103.12-name-constraint-bypass
    label: disclosure@vulncheck.com
  - url: 'https://crates.io/crates/rustls-webpki'
  - url: 'https://rustsec.org/advisories/RUSTSEC-2026-0099.html'
  - url: 'https://github.com/rustls/webpki'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93601.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-93601'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2538656'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-93601'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93601'
tags:
  - nvd
  - cve.org
  - osv
  - rust
  - csaf
  - vex
  - red-hat
epss: 0.00183
epssPercentile: 0.081
aliases:
  - RUSTSEC-2026-0099
  - GHSA-xgp8-3hg3-c2mh
ecosystem: rust
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-18T17:49:32.542670Z'
ingestedAt: '2026-09-18T13:41:41.663Z'
---

## Overview

rustls-webpki (the Rust webpki fork used by rustls) versions >= 0.101.0 and prior to 0.103.12 and 0.104.0-alpha.6 incorrectly accepted permitted-subtree DNS name constraints for certificates asserting a wildcard name. For example, a name constraint of accept.example.com was treated as satisfied by a certificate for *.example.com, which could feasibly assert reject.example.com — a name outside the permitted subtree. Because name constraints are restrictions applied to otherwise properly issued certificates, the issue is only reachable after signature verification succeeds and requires a misissued wildcard certificate to exploit.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-93601)

Affected packages:

- `rustls-webpki >= 0.104.0-alpha.1, < 0.104.0-alpha.6`

Patched in:

- `rustls-webpki 0.104.0-alpha.6`

Source: https://osv.dev/vulnerability/RUSTSEC-2026-0099

## Vendor advisories

- **Red Hat VEX** · Low · affected: Confidential Cluster Operator, Confidential Compute Attestation, Logging Subsystem for Red Hat OpenShift, Migration Toolkit for Applications 8, OpenShift Lightspeed, OpenShift Service Mesh 3, … · no fix planned: Logging Subsystem for Red Hat OpenShift, Migration Toolkit for Applications 8, Red Hat Ansible Automation Platform 2, Red Hat Ansible Automation Platform Ansible Core 2, … · updated 2026-09-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93601.json)