Vulnerability · Published Sep 27, 2026 · Assigned by VulnCheck

CVE-2026-100836Edgeless Systems Contrast through 1.20.0 Denial of Service via ciphertextContainer

Medium 4.3

In plain English

A medium-severity security flaw in contrast from edgelesssys. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.3Medium

Exploit odds (30 days)0.2%top 92.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

Contrast through 1.20.0 contains a panic vulnerability in the transit-engine endpoint's ciphertextContainer.UnmarshalJSON function that fails to validate decoded ciphertext length before slicing. An authenticated workload with a valid mesh certificate can trigger a runtime panic by submitting a short base64-encoded ciphertext, causing log spam and request failures without crashing the process.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/edgelesssys/contrast	1.21.0	GHSA-3ccm-4qq2-5wrp
Go	github.com/edgelesssys/contrast	1.21.0	GO-2026-5864

Affected products (as reported)

Vendor	Product	Versions
edgelesssys	contrast	0 – through 1.20.0

Weakness: CWE-129 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

References

GitHub Security Advisory (GHSA-3ccm-4qq2-5wrp) vendor-advisory
VulnCheck Advisory: Edgeless Systems Contrast through 1.20.0 Denial of Service via ciphertextContainer third-party-advisory