# CVE-2026-15779: Samba-winbind: samba: pam_winbind mkhomedir chowns critical system paths without validation

> Attackers with limited sudo access can trigger pam_winbind to change ownership of the root directory, causing severe system denial of service.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Jul 2026
- **Updated:** 15 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-15779, ECHO-9793-9b10-71e9, GHSA-6fmw-7w5g-3pf9, OESA-2026-3364, OESA-2026-3365, OESA-2026-3410, OESA-2026-3411, OESA-2026-3412, UBUNTU-CVE-2026-15779

## What is CVE-2026-15779?

CVE-2026-15779 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, published on 15 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A flaw was found in samba's pam_winbind. When mkhomedir is enabled, pam_winbind chowns the target account's home directory without validating the path is not a critical system directory such as /. On affected systems, accounts with / as their home directory (a common default for system accounts) can have this triggered not only by root, but by a non-root user holding a narrow sudo delegation to run commands as that account, causing ownership of / to change and resulting in severe denial of service (SSH, sudo, and package-manager failures). The change does not grant write access to / (which ships with restrictive 0555 permissions on RHEL), so the impact is availability loss rather than further privilege escalation.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource)

## Which versions are affected by CVE-2026-15779?


## How do I fix CVE-2026-15779?

Apply the vendor's patch.

## Is CVE-2026-15779 being exploited?

There is no known exploitation of CVE-2026-15779 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15779 and fix it if it is affected.

What it is: CVE-2026-15779 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, published on 15 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-15779 in the wild and no public exploit code.

Affected product: Red Hat Enterprise Linux 10. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-15779/ (Markdown: https://insights.sbomify.com/CVE-2026-15779/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15779
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15779
- OSV: https://osv.dev/vulnerability/CVE-2026-15779

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-15779/
Summaries are generated and may contain mistakes; the official description above is the record.