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Date: Wed, 6 Feb 2019 08:12:29 +0100 (CET)
From: Daniel Stenberg <>
To: curl security announcements -- curl users <>,,
        libcurl hacking <>,
Subject: [SECURITY ADVISORY] curl: NTLM type-2 out-of-bounds buffer read

NTLM type-2 out-of-bounds buffer read

Project curl Security Advisory, February 6th 2019 -


libcurl contains a heap buffer out-of-bounds read flaw.

The function handling incoming NTLM type-2 messages
(`lib/vauth/ntlm.c:ntlm_decode_type2_target`) does not validate incoming data
correctly and is subject to an integer overflow vulnerability.

Using that overflow, a malicious or broken NTLM server could trick libcurl to
accept a bad length + offset combination that would lead to a buffer read

We are not aware of any exploit of this flaw.


This bug was introduced in [commit
86724581b6c](, January 2014.

The Common Vulnerabilities and Exposures (CVE) project has assigned the name
CVE-2018-16890 to this issue.

CWE-125: Out-of-bounds Read

Severity: 5.3 (Medium)


- Affected versions: libcurl 7.36.0 to and including 7.63.0
- Not affected versions: libcurl < 7.36.0 and >= 7.64.0

libcurl is used by many applications, but not always advertised as such.


A [patch for CVE-2018-16890](


We suggest you take one of the following actions immediately, in order of

  A - Upgrade curl to version 7.64.0

  B - Apply the patch to your version and rebuild

  C - Turn off NTLM authentication


It was reported to the curl project on December 30, 2018. We contacted
distros@...nwall on January 28.

curl 7.64.0 was released on February 6 2019, coordinated with the publication
of this advisory.


Reported by Wenxiang Qian of Tencent Blade Team. Patch by Daniel Stenberg.

Thanks a lot!



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