---
title: "CVE-2026-100838: Contrast confidential-computing runtime - Arbitrary File Write"
description: "Contrast confidential-computing runtime for Kubernetes < 1.19.1 contains an arbitrary file write vulnerability caused by flawed CopyFile verification in Kata agent policies, letting malicious host processes overwrite guest root filesystem files, exploit requires connection to Kata agent VSOCK."
url: https://panop.io/threat-heartbeat/CVE-2026-100838/
---

# CVE-2026-100838 Contrast confidential-computing runtime - Arbitrary File Write

Contrast confidential-computing runtime for Kubernetes < 1.19.1 contains an arbitrary file write vulnerability caused by flawed CopyFile verification in Kata agent policies, letting malicious host processes overwrite guest root filesystem files, exploit requires connection to Kata agent VSOCK.

CVSS base score 8.1 /10

High

CISA KEV

Not listed

Public exploit

None known

EPSS

0.22% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-100838)

## Details

Type

Arbitrary File Write

Impact

File System Write, Information Disclosure

CVSS vector

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Published

27 September 2026

Updated

15 October 2026

Weakness

[CWE-59](https://cwe.mitre.org/data/definitions/59.html)

## Vendor fix

Upgrade to version 1.19.1 or apply the equivalent rego policy fix via 'contrast generate --policy'.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-100838](https://nvd.nist.gov/vuln/detail/CVE-2026-100838)
- [https://github.com/edgelesssys/contrast/security/advisories/GHSA-rh99-wc69-c255](https://github.com/edgelesssys/contrast/security/advisories/GHSA-rh99-wc69-c255)
- [https://www.vulncheck.com/advisories/contrast-before-1.19.1-copyfile-policy-symlink-subversion](https://www.vulncheck.com/advisories/contrast-before-1.19.1-copyfile-policy-symlink-subversion)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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