HashiCorp Consul CVE-2026-15970

Three specific conditions must all be true for exploitation: (1) the attacker must be an authenticated Consul mesh workload with valid service mesh credentials, confirmed by PR:L in the CVSS vector - unauthenticated external attackers cannot exploit this; (2) the target service proxy must be configured with a custom public listener, which is a non-default Consul configuration - deployments using only the default listener are not affected; (3) the target service must have active L7 path-based deny intentions protecting specific HTTP paths, as this flaw exclusively affects the path-matching logic of L7 intentions. High attack complexity (AC:H) further indicates the bypass is not trivially reproducible across all configurations. Services using only L4 intentions, no intentions, or default listeners have no exposure.

The CVSS 3.1 vector AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N yields 4.2 (Medium), and the individual metrics are well-calibrated to actual exploitation conditions. High attack complexity (AC:H) reflects the non-default prerequisite of a custom public listener; low privileges (PR:L) reflects the requirement for authenticated mesh workload credentials; scope is unchanged (S:U) and impact is partial (C:L/I:L), meaning only data readable or writable through the bypassed path is at risk. EPSS data was not provided in the input, so exploitation probability cannot be quantified. This CVE is not listed in CISA KEV and no public POC has been identified, making this a low-urgency issue for most organizations. However, for service mesh deployments that rely on L7 path-based deny intentions as a security boundary - for example, blocking admin endpoints or sensitive API routes - this is a genuine control failure that warrants timely patching. Organizations not using custom public listeners or path-based deny intentions face no exposure.

An attacker controlling an authenticated Consul mesh workload - such as a compromised microservice sidecar or a workload with valid mesh enrollment credentials - identifies a target service protected by L7 path-based deny intentions, where the proxy uses a custom public listener. The attacker crafts HTTP requests with non-canonical path representations that the intention evaluation engine fails to match against the deny rule, gaining read or write access to restricted HTTP endpoints such as admin APIs or sensitive data routes. Since no public POC exists, exploitation currently requires independent discovery or insider knowledge of the specific path canonicalization bypass.