# CVE-2026-58216: Samba KDC out-of-bounds read in kpasswd service

Source: https://junglewise.ai/threats/cve-2026-58216-samba-kdc-out-of-bounds-read-in-kpasswd-service  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-30. Updated: 2026-07-30  
License: CC BY 4.0 with a link back

CVE-2026-58216 · Severity: medium · CVSS 5.3 · Published 2026-07-30

Samba is a widely used suite of programs that allows Linux and Unix systems to share files and printers with Windows systems. A vulnerability in its password change service (kpasswd) could allow a logged-in user to crash the authentication server by sending a specially crafted request. While this does not allow the attacker to steal data, it can disrupt network operations by causing a denial of service.

Technologies: [Red Hat Enterprise Linux 10](https://junglewise.ai/threats/technologies/enterprise-linux-10), [Red Hat Enterprise Linux 6](https://junglewise.ai/threats/technologies/enterprise-linux-6), [Red Hat Enterprise Linux 7](https://junglewise.ai/threats/technologies/enterprise-linux-7), [Red Hat Enterprise Linux 8](https://junglewise.ai/threats/technologies/enterprise-linux-8), [Red Hat Enterprise Linux 9](https://junglewise.ai/threats/technologies/enterprise-linux-9), [Red Hat OpenShift Container Platform 4](https://junglewise.ai/threats/technologies/openshift-container-platform-4), [Samba](https://junglewise.ai/threats/technologies/samba). Vendors: [Red Hat](https://junglewise.ai/threats/vendors/red-hat), [Samba](https://junglewise.ai/threats/vendors/samba).

## Quick answers

**Is CVE-2026-58216 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-58216 being exploited in the wild.

**How severe is CVE-2026-58216?** Medium severity, with a CVSS score of 5.3, published 30 July 2026.

**Which products and versions are affected?** Red Hat Enterprise Linux 10 samba; Red Hat Enterprise Linux 6 samba, samba4; Red Hat Enterprise Linux 7 samba; Red Hat Enterprise Linux 8 samba; and 3 more.

**Is there a fix for CVE-2026-58216?** A patch was published on 2026-07-29: Samba bug resolved fixed Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-58216 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-58216?** Check whether you run Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds read vulnerability exists in Samba's KDC kpasswd service within 'source4/kdc/kpasswd-service.c'. The flaw is caused by a miscalculation of the encrypted data length in ASN.1-encoded Kerberos password change requests, where the code fails to subtract the 6-byte header length from the total packet length. An authenticated attacker can exploit this by sending a malformed request, forcing the server to read up to six bytes beyond the allocated buffer. While this typically results in a decryption failure, it can trigger a process crash (SIGSEGV) if the read crosses into unmapped memory. Fixes are available in Samba security releases, and a workaround exists by disabling the kpasswd service via 'kpasswd port = 0' in smb.conf.

## Affected products

- Samba Samba 4.0 and newer
- Red Hat Enterprise Linux 6 samba, samba4
- Red Hat Enterprise Linux 7 samba
- Red Hat Enterprise Linux 8 samba
- Red Hat Enterprise Linux 9 samba
- Red Hat Enterprise Linux 10 samba
- Red Hat OpenShift Container Platform 4 rhcos

## Timeline

- 2026-05-27: disclosed: Initial report to Samba by Tristan Madani
- 2026-07-30: advisory: NVD and Red Hat published advisory
- 2026-07-29: patched: Samba bug resolved fixed

## References

- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)
- [https://access.redhat.com/security/cve/CVE-2026-58216](https://access.redhat.com/security/cve/CVE-2026-58216)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2502721](https://bugzilla.redhat.com/show_bug.cgi?id=2502721)
- [https://bugzilla.samba.org/show_bug.cgi?id=16087](https://bugzilla.samba.org/show_bug.cgi?id=16087)
- [https://www.samba.org/samba/security/CVE-2026-58216.html](https://www.samba.org/samba/security/CVE-2026-58216.html)

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