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Samba CVE-2026-58216

| EUVDEUVD-2026-51177 MEDIUM
Out-of-bounds Read (CWE-125)
2026-07-30 redhat GHSA-vc9h-gm8g-6j4x
Buffer Overflow Denial Of Service Information Disclosure Red Hat Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9 Red Hat Openshift Container Platform 4 Suse Red Hat
5.3
CVSS 3.1 · Vendor: redhat
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Severity by source

Vendor (redhat) PRIMARY
5.3 MEDIUM
AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.3 MEDIUM

Network-reachable kpasswd service; AC:H because DoS requires probabilistic unmapped-memory hit; PR:L for required domain authentication; no confidentiality or integrity impact.

3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
5.3 MEDIUM
qualitative

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Analysis Generated
Jul 30, 2026 - 16:51 vuln.today
CVE Published
Jul 30, 2026 - 15:40 nvd
MEDIUM 5.3

DescriptionCVE.org

An out-of-bounds read flaw was found in Samba's Kerberos Key Distribution Center's (KDC) password change (kpasswd) service. When processing malformed ASN.1-encoded Kerberos password change request, Samba server miscalculates the structure size and attempts to read up to six bytes beyond the end of the allocated buffer. While this out-of-bounds read typically results in a harmless decryption failure, if the read hits unmapped memory, it causes the KDC process to crash. An authenticated attacker can send a specially crafted kpasswd request containing malformed ASN.1 data to trigger the out-of-bounds read, which may cause the KDC process to terminate, resulting in a denial of service.

AnalysisAI

Denial of service in Samba's Kerberos KDC password change (kpasswd) service allows authenticated remote attackers to crash the KDC process by submitting specially crafted, malformed ASN.1-encoded password change requests. The server miscalculates the structure size of the incoming request and reads up to six bytes beyond the end of the allocated buffer; when this read strikes unmapped memory, the KDC process terminates rather than simply failing gracefully. No public exploit has been identified and no CISA KEV listing exists, but the disruption of a KDC in an Active Directory or Samba domain environment carries significant operational impact since authentication for the entire domain depends on KDC availability.

Technical ContextAI

Samba implements the Kerberos Key Distribution Center (KDC) including the kpasswd service, which handles password change requests over UDP/TCP port 464 using ASN.1-encoded Kerberos protocol messages. The flaw is an out-of-bounds read (CWE-125) rooted in faulty size calculation when parsing the ASN.1 structure of a kpasswd request: the code computes a structure length incorrectly and subsequently reads up to six bytes past the end of the heap-allocated buffer. In most cases the stale or zeroed bytes read from adjacent allocated memory cause only a decryption failure, but if the overrun crosses into an unmapped virtual-memory page, the operating system delivers a SIGSEGV or similar signal that terminates the KDC process. Affected deployments according to CPE data span Red Hat Enterprise Linux 6 through 10 and Red Hat OpenShift Container Platform 4, all of which ship Samba as their domain controller implementation.

RemediationAI

A vendor-released patch is available per the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-58216 and the upstream Samba security advisory at https://www.samba.org/samba/security/CVE-2026-58216.html; administrators should apply the patched Samba packages for their RHEL or Ubuntu release via standard package management (yum/dnf update samba or apt-get upgrade samba). Exact fixed version numbers were not confirmed in the provided data - verify the specific patched package version against the vendor advisories before deploying. As a compensating control prior to patching, access to the kpasswd service (UDP/TCP port 464) can be restricted at the network perimeter or host firewall to only trusted hosts that require password changes, reducing the attacker pool to those already on trusted network segments; note that this may break password-change workflows for remote or off-network users. Deploying a secondary KDC (additional domain controller) as a redundancy measure limits availability impact even if the primary KDC is crashed, and is recommended regardless of patching status for production environments.

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Same weakness CWE-125 – Out-of-bounds Read

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Same technique Buffer Overflow

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
Container suse/samba-client:latest Container suse/samba-toolbox:latest Affected
Container suse/samba-server:latest Affected
Image SLES12-SP5-SAP-Azure-LI-BYOS-Production Image SLES12-SP5-SAP-Azure-VLI-BYOS-Production Affected
Image SLES15-SP7-BYOS-EC2 Affected
SUSE Enterprise Storage 7.1 Fixed

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CVE-2026-58216 vulnerability details – vuln.today
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