rustls webpki 0.101.0 before 0.103.12 Name Constraint Bypass
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- Present
- Impact type
- Spoofing
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- Partial Red Hat: 25 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-295.
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 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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| rustls | webpki | 0.101.0 to before 0.103.12; 0.104.0-alpha.1 to before 0.104.0-alpha.6 | 0.103.12, 0.104.0-alpha.6 | Patch available | CNA |
- webpki Vendorrustls Affected 0.101.0 to before 0.103.12; 0.104.0-alpha.1 to before 0.104.0-alpha.6 Fixed in 0.103.12, 0.104.0-alpha.6 Patch available CNA
Remediation
- Fix · CNA webpki (rustls) Fixed in 0.103.12, 0.104.0-alpha.6
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
rustls webpki 0.103.12, 0.104.0-alpha.6
2 records Highest priority Priority LOW 2 LOW
Other records, highest priority first
- TI-2026-63064 rustls webpki Name Constraints URI Validation BypassPriority LOW 11
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Ansible Automation Orchestrator 2026 | Affected | No fix yet: Fix deferred |
| Confidential Cluster Operator | Affected | No fix yet: Fix deferred |
| Confidential Compute Attestation | Affected | No fix yet: Fix deferred |
| Logging Subsystem for Red Hat OpenShift | Affected | No fix planned: Out of support scope |
| Migration Toolkit for Applications 8 | Affected | No fix planned: Out of support scope |
| OpenShift Lightspeed | Affected | No fix yet: Fix deferred |
| OpenShift Service Mesh 3 | Affected | No fix yet: Fix deferred |
| Pen Drive Powered by Red Hat Lightspeed | Affected | No fix yet: Fix deferred |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet: Fix deferred |
| Red Hat Ansible Automation Platform Ansible Core 2 | Affected | No fix yet: Fix deferred |
| Red Hat Discovery 2 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux command line assistant | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Update Service | Affected | No fix yet: Fix deferred |
| Red Hat Quay 3 | Affected | No fix yet: Fix deferred |
| Red Hat Satellite 6 | Affected | No fix yet: Fix deferred |
| Red Hat Trusted Artifact Signer | Affected | No fix yet: Fix deferred |
| Red Hat Trusted Profile Analyzer | Affected | No fix yet: Fix deferred |
Not affected: 1 product
- Red Hat Hardened Images
Timeline
- 2026-10-02 Threatist record created from CVE-2026-93601
- 2026-10-03 Alias added: GHSA-27hx-xqx9-p6hq
- 2026-10-30 Affected versions changed · Red Hat
References
More rustls vulnerabilities
- TI-2026-63063 rustls-webpki before 0.103.13 Panic via empty BIT STRING CVSS 4.0HIGH 8.7
- TI-2026-86755 Rustls accepts handshake messages at the wrong encryption level CVSS 4.0MEDIUM 6.9
- TI-2026-86753 Key exchange downgrade in rustls via unauthenticated ServerHello CVSS 4.0MEDIUM 6.3
- TI-2026-86752 Uncontrolled memory allocation in rustls Brotli certificate decompression CVSS 4.0MEDIUM 6.3
- TI-2024-21532 Rustls vulnerable to an infinite loop in rustls::conn::ConnectionCommon::complete_io() with proper client input CVSS 3.1HIGH 7.5
- TI-2026-86754 Application data sent to public_name server when rustls rejects ECH CVSS 4.0MEDIUM 4.6
Sources
- CVE-2026-93601 · CVE Program
- CVE-2026-93601 · NVD
- FIRST EPSS
- GHSA-27hx-xqx9-p6hq · GitHub Advisory Database · CC BY 4.0
- CVE-2026-93601 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences