# CVE-2026-100836: Edgeless Systems Contrast panic in ciphertextContainer.UnmarshalJSON

Source: https://junglewise.ai/threats/cve-2026-100836-contrast-through-1-20-0-contains-a-panic-vulnerability-in-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-27. Updated: 2026-09-27  
License: CC BY 4.0 with a link back

CVE-2026-100836 · Severity: medium · CVSS 4.3 · Published 2026-09-27

Contrast, a confidential computing security platform, contains a vulnerability in its transit-engine endpoint that crashes request handlers when processing malformed ciphertext data. An authenticated workload with valid mesh credentials can deliberately trigger these crashes, causing service disruptions and excessive logging. While the Coordinator process itself does not crash, repeated attacks can degrade performance and availability.

Technologies: [Edgeless Systems Contrast](https://junglewise.ai/threats/technologies/contrast). Vendors: [Edgeless Systems](https://junglewise.ai/threats/vendors/edgeless-systems).

## Quick answers

**Is CVE-2026-100836 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100836 being exploited in the wild.

**How severe is CVE-2026-100836?** Medium severity, with a CVSS score of 4.3, published 27 September 2026.

**Which products and versions are affected?** Edgeless Systems Contrast through 1.20.0.

**Is there a fix for CVE-2026-100836?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-100836 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-100836?** Check whether you run Edgeless Systems Contrast at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The ciphertextContainer.UnmarshalJSON function in the transit-engine API performs an unchecked slice operation on base64-decoded ciphertext without validating its length. If decoded ciphertext is shorter than 12 bytes (the AES-GCM nonce size), the slice expression panics at runtime. An authenticated workload holding a valid mesh certificate can trigger the panic repeatedly with minimal overhead, causing log spam and request handler aborts without requiring any special privileges or user interaction.

## Affected products

- Edgeless Systems Contrast through 1.20.0

## Timeline

- 2026-05-27: disclosed
- 2026-09-27: advisory

## References

- [https://github.com/edgelesssys/contrast/security/advisories/GHSA-3ccm-4qq2-5wrp](https://github.com/edgelesssys/contrast/security/advisories/GHSA-3ccm-4qq2-5wrp)
- [https://www.vulncheck.com/advisories/edgeless-systems-contrast-through-1.20.0-denial-of-service-via-ciphertextcontainer](https://www.vulncheck.com/advisories/edgeless-systems-contrast-through-1.20.0-denial-of-service-via-ciphertextcontainer)

## Related threats

- [Contrast improper verification in Coordinator peer recovery](https://junglewise.ai/threats/cve-2026-109359-contrast-1-8-0-before-1-24-1-contains-an-improper-verification)
- [Edgeless Systems Contrast privilege escalation in node installer](https://junglewise.ai/threats/cve-2026-109358-edgeless-systems-contrast-1-8-0-before-1-24-1-contains-an)
- [Edgeless Systems Contrast AML injection in ACPI handler](https://junglewise.ai/threats/cve-2026-100839-contrast-is-a-confidential-computing-runtime-for-kubernetes-in)
- [Edgeless Systems Contrast arbitrary filesystem write in CopyFile policy](https://junglewise.ai/threats/cve-2026-100838-contrast-is-a-confidential-computing-runtime-for-kubernetes-in)
- [Edgeless Systems Contrast remote attestation relay attack](https://junglewise.ai/threats/cve-2026-100835-contrast-before-1-16-0-is-susceptible-to-remote-attestation)