CVE-2026-100835 — Edgeless Contrast Remote Attestation Relay (aTLS)

Overview

CVE-2026-100835 affects Edgeless Systems Contrast before 1.16.0. Contrast attested TLS (aTLS) relied on remote attestation; prior to the fix, any cryptographically valid TEE attestation report matching ReferenceValues (firmware TCB, measurements) was treated as sufficient without binding the report to specific, physically trusted hardware (CWE-295).

An attacker who can intercept attestation traffic (CLI ↔ Coordinator or Coordinator ↔ workload) and controls any compatible TEE (or can extract relay secrets from a host) can relay a report and impersonate the Coordinator or a workload, breaking aTLS identity verification.

| | | |---|---| | Vendor / product | Edgeless Systems Contrast | | Affected | 0 < version < 1.16.0 | | Component | Remote attestation / aTLS | | Attack | Relay valid TEE report + MITM | | Mitigation | Upgrade ≥ 1.16.0 + populate AllowedChipIDs / AllowedPIIDs | | CWE | CWE-295 Improper Certificate Validation | | CVSS 4.0 | VulnCheck 9.1 CRITICAL |

Fixed release: 1.16.0 adds manifest fields AllowedChipIDs (SEV-SNP) and AllowedPIIDs (TDX). Operators must set IDs from physically audited hosts. Empty allowlists still accept any chip/PIID — relay remains possible until lists are configured.

Advisories: GHSA-hjgc-jc5v-fw7h, VulnCheck advisory

Open source PoC: https://github.com/murrez/CVE-2026-100835

PoC page: https://pocbit.org/pocs/cve-2026-100835

This PoC audits manifests, extracts Contrast versions from manifests/K8s YAML, probes Coordinator HTTP endpoints, and documents the relay chain. It does not perform MITM or TEE forgery.

Bundled tool (Python 3)

pip install -r requirements.txt

python poc.py --manifest manifest.json --contrast-version 1.15.0 --mode manifest
python poc.py -u https://coordinator.example:1313 --manifest manifest.json --mode check
python poc.py -u https://coordinator.example:1313 --mode exploit --print-chain
python poc.py --list targets.example.txt --manifest manifest.json -j 8
python poc.py --k8s deployment.yaml --manifest manifest.json --mode manifest

See manifest.example.json in the repo for how empty allowlists imply relay-config risk.

Impact

Successful relay undermines aTLS identity for the Contrast mesh — attackers may impersonate Coordinator or workloads and compromise mesh/workload secrets. Treat suspected exploitation per vendor incident response.

Remediation

1. Upgrade Contrast to 1.16.0 or newer.
2. Set AllowedChipIDs / AllowedPIIDs from audited hardware inventory (not empty in production).
3. Review attestation paths for MITM exposure; restrict Coordinator access.

Legal and ethical use

Authorized security research and your own deployments only.

References

• NVD — CVE-2026-100835
• GitHub PoC — murrez/CVE-2026-100835