CVE-2026-93600
LowCVSS 2.2Summary
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, accepting rather than enforcing them. These constraints apply to otherwise properly issued certificates, so the flaw is reachable after successful signature verification and requires a misissued certificate.
Risk Assessment
This may allow bypassing URI name constraints and trusting a certificate that should be rejected, potentially enabling man-in-the-middle attacks. Exploitation requires a misissued certificate.
Recommendation
Update rustls-webpki to version 0.103.12 or 0.104.0-alpha.6 or later, which unconditionally reject URI name constraints. Ensure certificates used are properly issued.
Other vulnerabilities in rustls-webpki
See all- CVE-2026-93602Medium
rustls-webpki versions before 0.103.10 and 0.104.0-alpha.5 contain faulty CRL authority-matching logic that compares only the first distributionPoint against each CRL's IssuingDistributionPoint, ignoring additional distributionPoints.
- CVE-2026-93601Low
rustls-webpki versions >= 0.101.0 and prior to 0.103.12 and 0.104.0-alpha.6 incorrectly accept permitted-subtree DNS name constraints for certificates asserting a wildcard name. For example, a name constraint of accept.example.com is treated as satisfied by a certificate for *.example.com, which could assert reject.example.com outside the permitted subtree.
- CVE-2026-93599High
rustls-webpki through 0.103.12 (and 0.104.0-alpha releases before 0.104.0-alpha.7) contains a reachable panic in bit_string_flags() in src/der.rs. The input guard fails to reject a named-bit BIT STRING with content exactly [0x00], causing an underflow and panic. Reachable via BorrowedCertRevocationList::from_der() when a CRL contains an issuingDistributionPoint extension with such an onlySomeReasons value. Requires an application that opts in to CRL revocation checking and parses attacker-influenced CRL bytes; default rustls configuration is unaffected. Fixed in 0.103.13 and 0.104.0-alpha.7.
Original NVD description (English source)
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.