Security Bulletin
Summary
HashiCorp Consul and Consul Enterprise 1.17.0 up to 2.0.4 are vulnerable to an authorization bypass in the agent's service mesh leaf certificate API that may allow an attacker without a valid ACL token to retrieve a cached service leaf certificate and its private key. This vulnerability (CVE-2026-105765) is fixed in Consul Community Edition 2.1.0 and Consul Enterprise 2.1.0 and 1.21.19.
Vulnerability Details
CVEID: CVE-2026-105765
DESCRIPTION: Consul agents enforced the service:write requirement only when a new leaf certificate had to be issued. When a valid certificate for the requested service was already cached on the agent, the agent returned it without verifying the caller's ACL token. An attacker with network access to the agent's HTTP API could retrieve that certificate and its private key without a valid ACL token, and could potentially use them to impersonate the service in the mesh and reach services that intentions permit for that identity. Exposure is limited to certificates already cached on the reachable agent, which typically includes services whose sidecar proxies are managed by that agent; Consul servers that manage proxies for Consul Dataplane deployments may cache certificates for many services. This issue only affects deployments with ACLs enabled. By default, the agent HTTP API listens only on the loopback interface, which limits exposure to processes on the same host.
CWE: CWE-862: Missing Authorization
CVSS Source: HashiCorp Inc.
CVSS Base score: 7.5
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
Affected Products and Versions
| Affected Product(s) | Version(s) |
| Consul Community Edition | affected from 1.17.0 up to 2.1.0 |
| Consul Enterprise | affected from 1.17.0 up to 2.1.0, unaffected from 1.21.19 |
Remediation/Fixes
Customers should evaluate the risk associated with this issue and consider upgrading to Consul Community Edition 2.1.0 or Consul Enterprise 2.1.0 or 1.21.19. Customers that cannot upgrade immediately may restrict network access to the agent HTTP API, or block the agent leaf certificate endpoint with http_config.block_endpoints if no Connect-native applications or consul-template configurations on that agent depend on it.
Get Notified about Future Security Bulletins
References
Link to HashiCorp Security Bulletin: https://discuss.hashicorp.com/t/hcsec-2026-46-consul-vulnerable-to-an-authorization-bypass-in-the-agents-service-mesh-leaf-certificate-api/77911
Acknowledgement
This issue was reported to HashiCorp by Tomas Castillo (https://github.com/muertostech).
Change History
26 Oct 2026: Initial Publication
*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.
Disclaimer
According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES ""AS IS"" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.
Document Location
Worldwide
Was this topic helpful?
Document Information
Modified date:
26 October 2026
Initial Publish date:
26 October 2026
UID
ibm17294114