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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.
This bug appears to have been reported against 'rawhide' during the Fedora Linux 45 development cycle. Changing version to 45.
FEDORA-2026-e5726efb1a (mqttcli-0.2.8-2.fc43) has been submitted as an update to Fedora 43. https://bodhi.fedoraproject.org/updates/FEDORA-2026-e5726efb1a
rawhide, f45 and f44 are not affected; they have been built with a version of golang >= 1.25.11. f43 was built with 1.25.5, so a rebuild with the latest golang on f43 (1.25.12) will mitigate this issue on f43.
FEDORA-2026-e5726efb1a has been pushed to the Fedora 43 testing repository. Soon you'll be able to install the update with the following command: `sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-e5726efb1a` You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-e5726efb1a See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
FEDORA-2026-e5726efb1a (mqttcli-0.2.8-2.fc43) has been pushed to the Fedora 43 stable repository. If problem still persists, please make note of it in this bug report.