Elastic Package Registry EUVD-2026-26140

Exploitation requires the attacker to occupy a network position capable of intercepting traffic between the Elastic client and the Elastic Package Registry (adversary-in-the-middle), OR to directly control or influence the content served by a self-hosted registry instance - for example, through compromise of the hosting server or storage backend. Exploitation is not feasible against clients consuming the official Elastic-hosted registry over an uncompromised TLS connection with valid certificate chain. The CVSS AC:H designation reflects this positional requirement. SSVC classifies the attack as non-automatable, confirming it requires deliberate, targeted effort rather than opportunistic mass scanning. No authentication is required once the network position is established; the flaw is in package integrity verification, not access control.

The CVSS 3.1 vector AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N scores 5.9 (Medium), reflecting that exploitation demands a high-complexity precondition - specifically, a network interception capability or control over a self-hosted registry. EPSS at 0.02% (6th percentile) confirms very low observed exploitation probability in the wild. SSVC further classifies exploitation as none, automatable as no, and technical impact as partial, all consistent with a constrained but meaningful supply-chain risk. No KEV listing and no public POC exist. The real-world priority is elevated specifically for organizations running self-hosted Elastic Package Registry instances in environments where MITM is plausible (e.g., shared or untrusted network segments, compromised TLS termination). Organizations consuming only the official Elastic-hosted registry over standard HTTPS without network interception face materially lower risk. There is no conflict between data sources; all signals converge on a credible but non-widespread threat.

An attacker with a MITM position on the network path between a Kibana or Elastic client and a self-hosted Elastic Package Registry intercepts a legitimate package download request and substitutes a crafted, malicious package in the response stream. Because the registry client's signature check fails open under this CWE-347 flaw, the tampered package is accepted and installed, potentially enabling code execution or data exfiltration within the Elastic Stack environment. No public POC is available, but the attack concept is well-understood within supply-chain security research.