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Fencer Vulns
medium 5.9

CVE-2023-25563 json

GSS-NTLMSSP vulnerable to multiple out-of-bounds reads when decoding NTLM fields

published 2023-02-14 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-29515

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 65%
public exploits
0
none known

Summary

GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, multiple out-of-bounds reads when decoding NTLM fields can trigger a denial of service. A 32-bit integer overflow condition can lead to incorrect checks of consistency of length of internal buffers. Although most applications will error out before accepting a singe input buffer of 4GB in length this could theoretically happen. This vulnerability can be triggered via the main `gss_accept_sec_context` entry point if the application allows tokens greater than 4GB in length. This can lead to a large, up to 65KB, out-of-bounds read which could cause a denial-of-service if it reads from unmapped memory. Version 1.2.0 contains a patch for the out-of-bounds reads.

Patch / fix

  • gss-ntlmssp_project gss-ntlmssp 1.2.0
  • gss-ntlmssp Debian 14, Debian 13, Debian 12 1.2.0-1

debian advisories DEBIAN-CVE-2023-25563

  • gss-ntlmssp Ubuntu Pro 16.04 LTS 0.7.0-3~ubuntu0.16.04.1+esm1
  • gss-ntlmssp Ubuntu Pro 18.04 LTS 0.7.0-4ubuntu0.18.04.1~esm1
  • gss-ntlmssp Ubuntu Pro 20.04 LTS 0.7.0-4ubuntu0.20.04.1~esm1
  • gss-ntlmssp Ubuntu Pro 22.04 LTS 0.7.0-4ubuntu0.22.04.1~esm1

ubuntu advisories UBUNTU-CVE-2023-25563

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

  • gssntlmssp RHEL 8 1.2.0-1.el8_8

red hat advisories RHSA-2023:3097

  • gssntlmssp Package Hub 15 SP4, openSUSE Leap 15.4 1.2.0-bp154.2.3.1

opensuse advisories openSUSE-SU-2023:0048-1

  • gssntlmssp AlmaLinux 8 1.2.0-1.el8_8

almalinux advisories ALSA-2023:3097

  • gssntlmssp Azure Linux 3.0 1.3.1-1

azure linux advisories AZL-44733

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-2023-25563 updated cvss 7.5

gssntlmssp: multiple out-of-bounds read when decoding NTLM fields

  • Red Hat Enterprise Linux AppStream (v. 8) gssntlmssp 1.2.0-1.el8_8
    fixed: vendor fix RHSA-2023:3097

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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
19 mo ago

Exploit prediction

1.09% chance of exploitation in the next 30 days, higher than 65% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • gssapi gss-ntlmssp

Classification

Weakness

References

Sources

Fencer Vulns 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.