CVE-2026-100833
Received Received - Intake

Contrast Policy Bypass via Kata Containers Image Substitution

Publication date: 2026-09-27

Last updated on: 2026-09-27

Assigner: VulnCheck

Description
Contrast (edgelesssys/contrast) versions 1.14.0 before 1.23.1 generate runtime policies that fail to detect all container image substitutions. A bad rebase during a Kata Containers update accidentally introduced an `allow_storage` rule that accepts storage entries using the `image_guest_pull` driver without verifying the image digest. An attacker with access to the Kata agent API — for example, a Kubernetes cluster administrator in Contrast's threat model — can therefore substitute a container image with an exploit payload, provided the substituted image satisfies the remaining policy rules, undermining the confidential container's integrity guarantees.

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Meta Information

Published
2026-09-27
Last Modified
2026-09-27
Generated
2026-09-27
AI Q&A
2026-09-27
EPSS Evaluated
N/A
NVD
CVE-2026-100833
EUVD
EUVD-2026-87853

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
edgelesssys contrast to 1.23.1 (exc)
edgelesssys contrast 1.23.1
edgelesssys contrast 1.24.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-20 The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

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Executive Summary

Contrast versions 1.14.0 to 1.23.1 have a flaw where runtime policies fail to detect container image substitutions. A bad rebase introduced an allow_storage rule that accepts storage entries using the image_guest_pull driver without verifying the image digest. Attackers with access to the Kata agent API, such as a Kubernetes cluster administrator, can substitute a container image with a malicious payload, bypassing integrity checks and compromising confidential containers.

Detection Guidance

To detect this vulnerability, check the Contrast version installed on your system. If it is between 1.14.0 and 1.23.0, it is vulnerable. Run: contrast version. Also inspect runtime policies for the vulnerable allow_storage rule using: cat /path/to/rules.rego | grep allow_storage. If the rule uses image_guest_pull without digest verification, the system is affected.

Additionally, monitor Kubernetes cluster administrator actions accessing the Kata agent API, as this is the attack vector. Check Kata agent logs for unauthorized image substitutions or policy changes.

Impact Analysis

An attacker with access to the Kata agent API could replace a legitimate container image with a malicious one, potentially leading to unauthorized code execution, data theft, or system compromise within confidential containers. This undermines the integrity guarantees of confidential computing environments.

Compliance Impact

This vulnerability could lead to unauthorized access or data breaches, violating confidentiality and integrity requirements in GDPR and HIPAA. Compliance may be compromised if unauthorized data access or tampering occurs due to the image substitution.

Mitigation Strategies

Immediately upgrade Contrast to version 1.23.1 or later. If upgrading is not possible, manually remove the vulnerable allow_storage rule from rules.rego and regenerate policies. Restrict access to the Kata agent API to only trusted administrators.

Audit all container images for unauthorized substitutions and verify their digests. Monitor runtime policies for any changes and ensure no allow_storage rules permit image_guest_pull without digest checks.

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