CVE-2019-3822: canonical ubuntu_linux Stack-based Buffer Overflow

Vulnerability summary

CVE-2019-3822 is a critical (CVSS 9.8) Stack-based Buffer Overflow vulnerability in canonical ubuntu_linux. EPSS estimates a 12.87% chance of exploitation in the next 30 days, higher than 96.2% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 06-02-2019
   PublishedVulnerability first disclosed.
2. 15-04-2026
   Last modifiedVulnerability information updated.

Description

libcurl versions from 7.36.0 to before 7.64.0 are vulnerable to a stack-based buffer overflow. 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 very large 'nt response' data is extracted from a previous NTLMv2 header provided by the malicious or broken HTTP server. Such a 'large value' 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.

• CWE-121Stack-based Buffer OverflowA stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.