GHSA-6c87-g9pw-78fx: Github.com/edgelesssys/contrast Contrast's Imagepuller RegistryFor Uses Unanchored Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6c87-g9pw-78fx",
  "modified" : "2026-07-01T18:43:56Z",
  "published" : "2026-07-01T18:43:55Z",
  "aliases" : [ ],
  "summary" : "Contrast's Imagepuller registryFor uses unanchored suffix matching, leaking auth credentials and trusted CA configuration to sibling-domain registries",
  "details" : "# Summary\n\n`Config.registryFor` selected a per-registry credential / CA / mirror block by checking `strings.HasSuffix(name, fqdn)` after stripping a single trailing dot. \nThe match has no boundary between the configured FQDN and any preceding characters in the request hostname.\nA registry configured as `[registries.\"ghcr.io.\"]` is therefore also applied to any image pulled from a host whose name happens to end in the literal byte sequence `ghcr.io`, \nincluding attacker-registered domains such as `evilghcr.io.` \nThe imagepuller would then send the configured `Authorization` header (basic auth, registry token, or identity token), trust the configured custom CA bundle,\nfollow the configured mirror, or honour `insecure-skip-verify`, on requests to that hostname.\n\n# Prerequisites\n\nFor this to be applicable, an image or layer must be pulled from a \"sibling\" domain ending in one of the FQDNs configured in the imagepuller config.\nThis may occur due to malicious intent or coincidentally.\n\n# Impact\n\n- Authentication header leaks to the sibling registry.\n- If `insecure-skip-verify` is set on an FQDN, TLS will also not be verified for the sibling registry.\n- Mirrors configured for an FQDN will also be used with the sibling registry.\n\n## Not impacted\n\nImage integrity is **not** impacted. Image bytes remain pinned by digest in the policy and are validated after the pull.\nThis advisory does not allow code substitution.\n\n# Workaround\n\n- If possible, configure explicit subdomains in the imagepuller config. A configuration for `[registries.\".example.registry\"]` is unaffected, only `[registries.\"example.registry\"]` is potentially affected.\n- Audit images and layers configured in the deployment for the existence of sibling domains.\n\n# Patches\n\nAfter this patch, registry matches are determined by exact label equality instead of suffix matching.\nEach `.`-separated part of the FQDN must be an exact match with the corresponding label in the image reference.\n\n# Severity\n\n- `AV:N` because the leak is over the network to a registry under the attacker's control. \n- `AC:H` because exploitation requires the operator to have configured a registry FQDN without a leading `.` AND the attacker to control a sibling-suffix domain that the deployment will pull from.\n- `PR:N` for the eventual recipient. \n- `S:U` because impact stays in the imagepuller. \n- `C:L` for credential leak (no integrity / availability impact).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/edgelesssys/contrast"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.21.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.20.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/edgelesssys/contrast/security/advisories/GHSA-6c87-g9pw-78fx"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/edgelesssys/contrast/commit/10826b1d82613025767fb094e8aa51a7dcfbd2a1"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/edgelesssys/contrast"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/edgelesssys/contrast/releases/tag/v1.21.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1289" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-01T18:43:55Z",
    "nvd_published_at" : null
  }
}