Vulnerability
curl/libcurl: printf floating point buffer overflow
libcurl's implementation of the printf() functions triggers a buffer overflow when doing a large floating point output. The bug occurs when the conversion outputs more than 255 bytes. The flaw happens because the floating point conversion is using system functions without the correct boundary checks. The functions have been documented as deprecated for a long time and users are discouraged from using them in "new programs" as they are planned to get removed at a future point. Since the functions are present and there is nothing preventing users from using them, we expect there to be a certain amount of existing users in the wild. If there are any application that accepts a format string from the outside without necessary input filtering, it could allow remote attacks. This flaw does not affect the curl command line tool.
No CVSS 3.x base score yet. Since April 2026 NVD only enriches priority CVEs (KEV, federal and critical software), so most CVEs are scored only if the assigning CNA included a score in the CVE record, or by GHSA for open-source packages. Last record update .
For interim severity, fall back on KEV / EXPLOIT signals and the EPSS percentile (lower panel). Re-check this CVE after one cron tick — the score lands automatically when the source publishes.
Mid-pack — moderate exploitation likelihood.
No VEX statements published for CVE-2016-9586. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.
No exploitation, limited impact or prevalence