Bug 2559964

Summary: CVE-2026-93601 maturin: rustls-webpki: Name Constraint Bypass in wildcard certificate validation [fedora-all]
Product: [Fedora] Fedora Reporter: Ronit Dey <rdey>
Component: maturinAssignee: Fabio Valentini <decathorpe>
Status: CLOSED NOTABUG QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: rawhideCC: code, decathorpe, python-packagers-sig, rust-sig
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["94568926-7455-4c8f-8f71-63ce67f08abb"]}
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Clone Of: Environment:
Last Closed: 2026-10-23 20:48:10 UTC Type: ---
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2538656    

Description Ronit Dey 2026-10-23 15:49:38 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.

Comment 1 Ben Beasley 2026-10-23 20:48:10 UTC
While rustls-webpki is in the upstrem Cargo.lock file, maturin as we build it doesn’t use that crate. This can be proved by looking at the LICENSE.dependencies file.

(We’ve also had rust-rustls-webpki at 0.103.12 or later for about six months. All maturin branches have been rebuilt and had updates issued since then except for EPEL10.2.)