Detections
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Amazon Linux 2023 : krb5-devel, krb5-libs, krb5-pkinit (ALAS2023-2026-1680)
medium Nessus Plugin ID 315640
Language:
Synopsis
The remote Amazon Linux 2023 host is missing a security update.Description
It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1680 advisory.In MIT Kerberos 5 (aka krb5) before 1.22.3, there is a NULL pointer dereference if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, causing the process to terminate in parse_nego_message.
(CVE-2026-40355)
In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message. (CVE-2026-40356)
Tenable has extracted the preceding description block directly from the tested product security advisory.
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.
Solution
Run 'dnf update krb5 --releasever 2023.11.20260511' or or 'dnf update --advisory ALAS2023-2026-1680 --releasever 2023.11.20260511' to update your system.See Also
https://alas.aws.amazon.com//AL2023/ALAS2023-2026-1680.html
https://alas.aws.amazon.com/faqs.html
Plugin Details
Severity: Medium
ID: 315640
File Name: al2023_ALAS2023-2026-1680.nasl
Version: 1.1
Type: Local
Agent: unix
Published: 5/20/2026
Updated: 5/20/2026
Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 4.4
CVSS v2
Risk Factor: Medium
Base Score: 5.4
Temporal Score: 4
Vector: CVSS2#AV:N/AC:H/Au:N/C:N/I:N/A:C
CVSS Score Source: CVE-2026-40356
CVSS v3
Risk Factor: Medium
Base Score: 5.9
Temporal Score: 5.2
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
CPE: p-cpe:/a:amazon:linux:krb5-debuginfo, p-cpe:/a:amazon:linux:krb5-devel, p-cpe:/a:amazon:linux:krb5-libs, p-cpe:/a:amazon:linux:krb5-pkinit, p-cpe:/a:amazon:linux:krb5-server, p-cpe:/a:amazon:linux:krb5-server-ldap, p-cpe:/a:amazon:linux:krb5-workstation, p-cpe:/a:amazon:linux:libkadm5, p-cpe:/a:amazon:linux:krb5-debugsource, p-cpe:/a:amazon:linux:krb5-libs-debuginfo, p-cpe:/a:amazon:linux:krb5-pkinit-debuginfo, p-cpe:/a:amazon:linux:krb5-server-debuginfo, p-cpe:/a:amazon:linux:krb5-server-ldap-debuginfo, p-cpe:/a:amazon:linux:krb5-workstation-debuginfo, p-cpe:/a:amazon:linux:libkadm5-debuginfo, cpe:/o:amazon:linux:2023
Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list
Exploit Ease: No known exploits are available
Patch Publication Date: 5/14/2026
Vulnerability Publication Date: 4/28/2026
Reference Information
CVE: CVE-2026-40355, CVE-2026-40356