The xsltAddTextString function in transform.c in libxslt 1.1.29, as used in Nokogiri prior to 1.7.2, lacked a check for integer overflow during a size calculation, which allowed a remote attacker to perform an out of bounds memory write via a crafted HTML page.
git.gnome.org/browse/libxslt/commit/?id=08ab2774b870de1c7b5a48693df75e8154addae5
github.com/advisories/GHSA-pf6m-fxpq-fg8v
github.com/rubysec/ruby-advisory-db/blob/master/gems/nokogiri/CVE-2017-5029.yml
github.com/sparklemotion/nokogiri
github.com/sparklemotion/nokogiri/issues/1634
nvd.nist.gov/vuln/detail/CVE-2017-5029
ubuntu.com/security/CVE-2017-5029
ubuntu.com/security/notices/USN-3271-1