Bug 2494249

Summary: CVE-2026-27145 opkssh: golang crypto/x509: Denial of Service via excessive processing of DNS SAN entries [epel-all]
Product: [Fedora] Fedora EPEL Reporter: jkelly <jkelly>
Component: opksshAssignee: Till Hofmann <thofmann>
Status: ON_QA --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: epel10CC: go-sig, thofmann
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:
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Clone Of: Environment:
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Documentation: --- CRM:
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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 14:14:51 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 Fedora Update System 2026-07-02 21:14:15 UTC 
FEDORA-EPEL-2026-229e7ad5a2 (opkssh-0.15.0-2.el10_3) has been submitted as an update to Fedora EPEL 10.3.
https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2026-229e7ad5a2
Comment 2 Fedora Update System 2026-07-02 21:16:44 UTC 
FEDORA-EPEL-2026-2dad2b9f74 (opkssh-0.15.0-2.el10_2) has been submitted as an update to Fedora EPEL 10.2.
https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2026-2dad2b9f74
Comment 3 Fedora Update System 2026-07-03 01:19:37 UTC 
FEDORA-EPEL-2026-2dad2b9f74 has been pushed to the Fedora EPEL 10.2 testing repository.

You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2026-2dad2b9f74

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 4 Fedora Update System 2026-07-03 01:33:22 UTC 
FEDORA-EPEL-2026-229e7ad5a2 has been pushed to the Fedora EPEL 10.3 testing repository.

You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2026-229e7ad5a2

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.