Vulnerability · Published Sep 27, 2026 · Assigned by VulnCheck
CVE-2026-100837Edgeless Systems Contrast through 1.20.0 Credential Leak via Registry Suffix Matching
Low 3.7
In plain English
A low-severity security flaw in contrast from edgelesssys. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Contrast (Edgeless Systems) through 1.20.0 performs unanchored suffix matching when selecting per-registry configuration in the imagepuller. Config.registryFor strips a single trailing dot and then uses strings.HasSuffix(hostname, fqdn) without requiring a DNS label boundary, so a registry entry such as [registries."ghcr.io."] is also applied to any host whose name merely ends in that byte sequence, including attacker-registered domains such as evilghcr.io. When an image or layer is pulled from such a sibling domain, the imagepuller sends the configured Authorization header (basic auth, registry token, or identity token), trusts the configured custom CA bundle, follows the configured mirror, and honours insecure-skip-verify (disabling TLS verification) for that host. Image integrity is not affected, as image bytes remain pinned by digest in the policy and are validated after the pull. Configurations that use a leading dot (e.g., [registries.".example.registry"]) are unaffected.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/edgelesssys/contrast | 1.21.0 | GHSA-6c87-g9pw-78fx |
| Go | github.com/edgelesssys/contrast | 1.21.0 | GO-2026-5865 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| edgelesssys | contrast | 0 – through 1.20.0 |
Weakness: CWE-1289 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N