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CVE-2019-3822

Published: 6 February 2019

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.

Notes

AuthorNote
mdeslaur
affects libcurl 7.36.0 to and including 7.63.0

Priority

Medium

Cvss 3 Severity Score

9.8

Score breakdown

Status

Package Release Status
curl
Launchpad, Ubuntu, Debian
upstream
Released (7.64.0)
trusty Not vulnerable
(code not present)
xenial
Released (7.47.0-1ubuntu2.12)
bionic
Released (7.58.0-2ubuntu3.6)
cosmic
Released (7.61.0-1ubuntu2.3)

Severity score breakdown

Parameter Value
Base score 9.8
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H