A bug in APR-util version 1.6.3 (and earlier) allows a stack recursion attack against any library consumer which parses XML from untrusted sources and uses the apr_xml_quote_elem() function.
Users are recommended to upgrade to version 1.6.4, which fixes this issue.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:HI:NA:H9.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:HOther