Vulnerability · Published Sep 18, 2026 · Assigned by VulnCheck
CVE-2026-93600rustls webpki Name Constraints URI Validation Bypass
Low 2.2
In plain English
A low-severity improper certificate validation in webpki from rustls. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
rustls-webpki (rustls/webpki) versions 0.101.0 through 0.103.11 and 0.104.0-alpha releases before 0.104.0-alpha.6 ignore X.509 name constraints that apply to URI names, causing such constraints to be accepted rather than enforced. Because name constraints are restrictions on otherwise properly issued certificates, the flaw is only reachable after successful signature verification and requires a misissued certificate to exploit; the library also provides no API for asserting URI names, and URI name constraints are otherwise unimplemented. Versions 0.103.12 and 0.104.0-alpha.6 reject URI name constraints unconditionally.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | rust-rustls-webpki | no fix listed | DEBIAN-CVE-2026-93600 |
| Debian:14 | rust-rustls-webpki | 0.103.13+ds-1 | DEBIAN-CVE-2026-93600 |
| Ubuntu:24.04:LTS | rust-rustls-webpki | no fix listed | UBUNTU-CVE-2026-93600 |
| Ubuntu:26.04:LTS | rust-rustls-webpki | no fix listed | UBUNTU-CVE-2026-93600 |
Affected products (as reported)
Weakness: CWE-295 · Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:N
References
- GitHub Security Advisory (GHSA-965h-392x-2mh5) vendor-advisory
- VulnCheck Advisory: rustls webpki Name Constraints URI Validation Bypass third-party-advisory