Vulnerability
curl/libcurl: NTLMv2 type-3 header stack buffer overflow
libcurl contains a stack based buffer overflow vulnerability. The function creating an outgoing NTLM type-3 header (`lib/vauth/ntlm.c:Curl_auth_create_ntlm_type3_message()`), generates the request HTTP header contents based on previously received data. The check that exists to prevent the local buffer from getting overflowed is implemented wrongly (using unsigned math) and as such it does not prevent the overflow from happening. This output data can grow larger than the local buffer if large response data is extracted from a previous NTLMv2 header provided by the malicious or broken HTTP server. Such large response data needs to be around 1000 bytes or more. The actual payload data copied to the target buffer comes from the NTLMv2 type-2 response header.
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.
Above the FIRST 'patch on a priority schedule' threshold.
No VEX statements published for CVE-2019-3822. 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