Debian dla-4603 : krb5-admin-server - security update

medium Nessus Plugin ID 317482

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Synopsis

The remote Debian host is missing one or more security-related updates.

Description

The remote Debian 11 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-4603 advisory.

------------------------------------------------------------------------- Debian LTS Advisory DLA-4603-1 [email protected] https://www.debian.org/lts/security/ Emmanuel Arias May 28, 2026 https://wiki.debian.org/LTS
-------------------------------------------------------------------------

Package : krb5 Version : 1.18.3-6+deb11u8 CVE ID : CVE-2026-40355 CVE-2026-40356 Debian Bug : 1135317

Two vulnerabilities was found in krb5, the MIT implementation of Kerberos, that an unauthenticated remote attacker can take advantage of these vulnerabilities to cause a denial of service.

CVE-2026-40355

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 a null pointer dereference, causing the process to terminate.

CVE-2026-40356

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 a read overrun of up to 52 bytes, possibly causing the process to terminate. Exfiltration of the bytes read does not appear possible.

For Debian 11 bullseye, these problems have been fixed in version 1.18.3-6+deb11u8.

We recommend that you upgrade your krb5 packages.

For the detailed security status of krb5 please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/krb5

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS Attachment:
signature.asc Description: PGP signature

Tenable has extracted the preceding description block directly from the Debian 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

Upgrade the krb5-admin-server packages.

Plugin Details

Severity: Medium

ID: 317482

File Name: debian_DLA-4603.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Debian Local Security Checks

Published: 5/29/2026

Updated: 5/29/2026

Supported Sensors: Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.6

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: cpe:/o:debian:debian_linux:11.0, p-cpe:/a:debian:debian_linux:krb5-pkinit, p-cpe:/a:debian:debian_linux:libkrb5support0, p-cpe:/a:debian:debian_linux:krb5-gss-samples, p-cpe:/a:debian:debian_linux:libkrad0, p-cpe:/a:debian:debian_linux:libkadm5clnt-mit12, p-cpe:/a:debian:debian_linux:libkrad-dev, p-cpe:/a:debian:debian_linux:krb5-kdc, p-cpe:/a:debian:debian_linux:krb5-otp, p-cpe:/a:debian:debian_linux:krb5-admin-server, p-cpe:/a:debian:debian_linux:libgssapi-krb5-2, p-cpe:/a:debian:debian_linux:libkrb5-dev, p-cpe:/a:debian:debian_linux:libkdb5-10, p-cpe:/a:debian:debian_linux:krb5-multidev, p-cpe:/a:debian:debian_linux:libgssrpc4, p-cpe:/a:debian:debian_linux:libk5crypto3, p-cpe:/a:debian:debian_linux:libkrb5-dbg, p-cpe:/a:debian:debian_linux:krb5-locales, p-cpe:/a:debian:debian_linux:krb5-user, p-cpe:/a:debian:debian_linux:libkadm5srv-mit12, p-cpe:/a:debian:debian_linux:libkrb5-3, p-cpe:/a:debian:debian_linux:krb5-kpropd, p-cpe:/a:debian:debian_linux:krb5-doc, p-cpe:/a:debian:debian_linux:krb5-k5tls, p-cpe:/a:debian:debian_linux:krb5-kdc-ldap

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Ease: No known exploits are available

Patch Publication Date: 5/28/2026

Vulnerability Publication Date: 4/28/2026

Reference Information

CVE: CVE-2026-40355, CVE-2026-40356

Detections

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