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Fencer Intel
critical 9.8

CVE-2019-17455 json

Libntlm through 1.5 relies on a fixed buffer size for tSmbNtlmAuthRequest, tSmbNtlmAuthChallenge, and tSmbNtlmAuthResponse read and write o…

published 2019-10-10 7 y ago modified 2026-06-17 4 mo ago also EUVD-2019-7844

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.1%
EPSS 3.1% chance of exploitation in 30 days, percentile 87%
public exploits
0
none known

Summary

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.

Patch / fix

  • libntlm Debian 14, Debian 13, Debian 12 1.6-1

debian advisories DEBIAN-CVE-2019-17455

  • libntlm Ubuntu 18.04 LTS 1.4-8ubuntu0.1
  • libntlm Ubuntu 20.04 LTS 1.5-2ubuntu0.1
  • libntlm Ubuntu Pro 14.04 LTS 1.4-1ubuntu0.1~esm1
  • libntlm Ubuntu Pro 16.04 LTS 1.4-7ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2019-17455

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libntlm Package Hub 15 SP1 1.6-bp151.4.3.1
  • libntlm openSUSE Leap 15.1 1.6-lp151.3.3.1

opensuse advisories openSUSE-SU-2020:0816-1openSUSE-SU-2020:0806-1

  • libntlm CBL-Mariner 2.0 1.6-1

azure linux advisories AZL-7266

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-17455 updated cvss 8.1

libntlm: stack-based buffer overflow in buildSmbNtlmAuthRequest in smbutil.c

  • Red Hat Enterprise Linux 6 libntlm
    affected: workaround, no fix planned “The calling application must verify that the input username and domain fit in the 1024 byte buffer.”
  • Red Hat Enterprise Linux 7 libntlm
    affected: workaround, no fix available “The calling application must verify that the input username and domain fit in the 1024 byte buffer.”
  • Red Hat Satellite 5 libntlm
    affected: workaround, no fix planned “The calling application must verify that the input username and domain fit in the 1024 byte buffer.”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.11% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • gitlab.com https://gitlab.com/jas/libntlm/issues/2 referenced PoC, tagged "exploit" by a source, unverified
  • bugs.debian.org https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=942145 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.