CVE-2026-58216

Samba: kpasswd service: kpasswd packet that contains malformed asn.1 might cause the server to access 6 bytes of unallocated memory leading server to crash

Published Jul 30, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

Vendor Workaround

Administrators who do not require the Kerberos password change service may disable it by setting ```kpasswd port = 0``` in ```/etc/samba/smb.conf```. Where disabling the service is not practical, rate-limiting access to the kpasswd service may reduce the likelihood of successful exploitation until an updated package can be applied. Note: Disabling kpasswd port will prevent domain users from changing their Kerberos passwords via the kpasswd protocol until patched.

Tracking

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Advisories

Source ID Title
Debian DSA Debian DSA DSA-6401-1 samba security update
Ubuntu USN Ubuntu USN USN-8621-1 Samba vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Redhat openshift Container Platform
Samba
Samba samba
Vendors & Products Redhat openshift Container Platform
Samba
Samba samba
Type Values Removed Values Added
Description 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.
Title Samba: kpasswd service: kpasswd packet that contains malformed asn.1 might cause the server to access 6 bytes of unallocated memory leading server to crash
First Time appeared Redhat
Redhat enterprise Linux
Redhat openshift
Weaknesses CWE-125
CPEs cpe:/a:redhat:openshift:4
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat openshift
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Jul 31, 2026, 10:57 PM
Reserved
Jun 29, 2026, 6:13 PM
Status
Awaiting Analysis
Published
Jul 30, 2026, 4:17 PM
Modified
Jul 31, 2026, 11:17 PM
Severity
Moderate
Public date
Jul 28, 2026, 10:00 AM