Bug 1768463 (CVE-2019-17455) - CVE-2019-17455 libntlm: stack-based buffer overflow in buildSmbNtlmAuthRequest in smbutil.c
Summary: CVE-2019-17455 libntlm: stack-based buffer overflow in buildSmbNtlmAuthReques...
Alias: CVE-2019-17455
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1768464 1768465 1771558 1771559 1771560
Blocks: 1768466
TreeView+ depends on / blocked
Reported: 2019-11-04 14:06 UTC by Guilherme de Almeida Suckevicz
Modified: 2021-10-25 09:54 UTC (History)
5 users (show)

Fixed In Version: libntlm 1.6
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the libntlm NTLM library where it was vulnerable to a buffer overflow in the buildSmbNtlmAuthRequest_userlen() function. If an application using this library does not check input length before calling the function, an attacker could use this flaw to send a specially crafted request that could crash the application, or possibly trigger code execution.
Clone Of:
Last Closed: 2021-10-25 09:54:12 UTC

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Description Guilherme de Almeida Suckevicz 2019-11-04 14:06:43 UTC
Libntlm through 1.5 relies on a fixed buffer size for tSmbNtlmAuthRequest, tSmbNtlmAuthChallenge, and tSmbNtlmAuthResponse read and write operations, as demonstrated by a stack-based buffer over-read in buildSmbNtlmAuthRequest in smbutil.c for a crafted NTLM request.


Comment 1 Guilherme de Almeida Suckevicz 2019-11-04 14:07:04 UTC
Created libntlm tracking bugs for this issue:

Affects: epel-7 [bug 1768465]
Affects: fedora-all [bug 1768464]

Comment 4 Cedric Buissart 2020-02-05 17:24:47 UTC

The calling application must verify that the input  username and domain fit in the 1024 byte buffer.

Comment 5 Cedric Buissart 2020-03-19 11:29:31 UTC

The vulnerability is rated Medium because no package in Red Hat Enterprise Linux versions 6 and 7 is using Libntlm. Most 3rd party applications using Libntlm are command line clients and would be affected via a command line option or a configuration file, which are local vectors.

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