# CVE-2026-100839: Contrast before 1.18.0 AML Injection Remote Code Execution

> A malicious host can inject AML bytecode to execute arbitrary code and access confidential data in Contrast guest kernels.

- **Severity:** High 8.4 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA: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:** 27 Sep 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-g9ww-x58f-9g6m, GHSA-qm93-38mp-vr3v, GO-2026-4863

## What is CVE-2026-100839?

CVE-2026-100839 is a high-severity code injection vulnerability in edgelesssys contrast, published on 27 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Contrast is a confidential-computing runtime for Kubernetes. In versions before 1.18.0, the guest kernel's ACPI/AML handling is vulnerable to an AML injection attack ("BadAML"). ACPI tables containing AML bytecode are passed from the untrusted host (QEMU) to the guest firmware (OVMF) and on to the Linux kernel, whose AML interpreter executes them. An attacker controlling the host — an assumed adversary in Contrast's threat model — can craft a table with malicious, Turing-complete AML bytecode that the guest kernel interprets with access to the full guest memory, including private pages, resulting in arbitrary code execution and disclosure or modification of confidential guest data. The issue affects the AMD SEV-SNP platforms Metal-QEMU-SNP and Metal-QEMU-SNP-GPU; Metal-QEMU-TDX is not affected because ACPI table contents are measured into RTMR 0 by OVMF on Intel TDX. Version v1.18.0 mitigates the attack by sandboxing the kernel AML interpreter so that it cannot read or write private memory pages. This weakness is not specific to Contrast but is generic to Confidential Computing setups that expose the ACPI interface to the host.

Weakness: CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2026-100839?

3 open source packages ship an affected version, including github.com/edgelesssys/contrast.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/edgelesssys/contrast` | Go | All versions | 1.18.0 |
| `github.com/edgelesssys/contrast` | Go | All versions | 1.18.0 |
| `github.com/edgelesssys/contrast` | Go | All versions | 1.18.0 |

## How do I fix CVE-2026-100839?

Upgrade github.com/edgelesssys/contrast to 1.18.0 or later.

## Is CVE-2026-100839 being exploited?

There is no known exploitation of CVE-2026-100839 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-100839 and fix it if it is affected.

What it is: CVE-2026-100839 is a high-severity code injection vulnerability in edgelesssys contrast, published on 27 Sep 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-2026-100839 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/edgelesssys/contrast (Go): affected all versions; fixed in 1.18.0
- github.com/edgelesssys/contrast (Go): affected all versions; fixed in 1.18.0
- github.com/edgelesssys/contrast (Go): affected all versions; fixed in 1.18.0

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-2026-100839/ (Markdown: https://insights.sbomify.com/CVE-2026-100839/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-100839
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-100839
- OSV: https://osv.dev/vulnerability/CVE-2026-100839

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-100839/
Summaries are generated and may contain mistakes; the official description above is the record.