Bug 2494400

Summary: CVE-2026-27145 pywhispercpp: golang crypto/x509: Denial of Service via excessive processing of DNS SAN entries [fedora-all]
Product: [Fedora] Fedora Reporter: jkelly <jkelly>
Component: pywhispercppAssignee: Manish Tiwari <matiwari>
Status: CLOSED NOTABUG QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: rawhideCC: matiwari
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["1765a0c8-adb1-4223-88bf-d35a230e256a"]}
Fixed In Version: Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2026-07-01 19:23:38 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2484207    

Description jkelly 2026-06-29 14:30:41 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.

(*x509.Certificate).VerifyHostname previously called matchHostnames in a loop over all DNS Subject Alternative Name (SAN) entries. This caused strings.Split(host, ".") to execute repeatedly on the same input hostname. With a large DNS SAN list, verification costs scaled quadratically based on the number of SAN entries multiplied by the hostname's label count. Because x509.Verify validates hostnames before building the certificate chain, this overhead occurred even for untrusted certificates.
Comment 1 Manish Tiwari 2026-07-01 19:23:38 UTC 
pywhispercpp does not use Go. It is a Python binding for whisper.cpp, which is written entirely in C and C++.