CVE-2026-58216

Summary

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.

Affected Software

VendorProductVersion RangeStatus

Weaknesses

  • CWE-125: Out-of-bounds Read

Workarounds

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.

References