CVE-2026-93600 rustls webpki Name Constraints URI Validation Bypass

What is CVE-2026-93600?

CVE-2026-93600 is a low-severity vulnerability in rustls webpki, published on 18 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.

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.

Weakness: CWE-295

Which versions are affected by CVE-2026-93600?

5 open source packages ship an affected version, including rustls-webpki.

How do I fix CVE-2026-93600?

Upgrade rustls-webpki to a fixed version for your release line: 0.103.12 or 0.104.0-alpha.6.

Is CVE-2026-93600 being exploited?

There is no known exploitation of CVE-2026-93600 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• GitHub advisory
• How this page is made

Also known as AZL-103466, AZL-103496, AZL-103515, AZL-103527, CLEANSTART-2026-SK45951, DEBIAN-CVE-2026-93600 and 28 more.