# CVE-2026-77159: Libvirt: unsafe chown in qemutpmemulatorpreparehost() allows arbitrary file ownership change via symlink

> A local attacker can exploit a symlink flaw in libvirt's TPM emulator to change ownership of arbitrary files, potentially leading to privilege escalation.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N`)
- **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:** 11 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** AZL-101739, BELL-CVE-2026-77159, DEBIAN-CVE-2026-77159, GHSA-wmhq-5pq5-8474, OESA-2026-4059, UBUNTU-CVE-2026-77159

## What is CVE-2026-77159?

CVE-2026-77159 is a medium-severity path traversal vulnerability in Red Hat Enterprise Linux 10, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A symlink-following flaw was found in libvirt's qemuTPMEmulatorPrepareHost() function. The function uses a path-based chown() on the swtpm logfile without checking for symbolic links. A local attacker with access to the swtpm account can replace the logfile with a symlink, causing libvirtd (running as root) to transfer ownership of an arbitrary file to the swtpm user.

Weakness: CWE-61 (UNIX Symbolic Link (Symlink) Following)

## Which versions are affected by CVE-2026-77159?


## How do I fix CVE-2026-77159?

Apply the vendor's patch.

## Is CVE-2026-77159 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77159 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77159 and fix it if it is affected.

What it is: CVE-2026-77159 is a medium-severity path traversal vulnerability in Red Hat Enterprise Linux 10, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77159 exists.

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-2026-77159/ (Markdown: https://insights.sbomify.com/CVE-2026-77159/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77159
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77159
- OSV: https://osv.dev/vulnerability/CVE-2026-77159

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77159/
Summaries are generated and may contain mistakes; the official description above is the record.