CVE-2026-5052
Published: 17 April 2026
Summary
CVE-2026-5052 is a medium-severity SSRF (CWE-918) vulnerability in Hashicorp Vault. Its CVSS base score is 5.3 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 24.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-5052 is a vulnerability in HashiCorp Vault's PKI engine ACME validation process, which fails to reject local targets when issuing http-01 and tls-alpn-01 challenges. This flaw allows requests to be sent to local network targets, potentially resulting in information disclosure. The issue affects Vault Community Edition and Vault Enterprise versions prior to the fixed releases, including Community Edition 2.0.0 and Enterprise 2.0.0, 1.21.5, 1.20.10, and 1.19.16. It is classified under CWE-918 (Server-Side Request Forgery) with a CVSS v3.1 base score of 5.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N).
Remote unauthenticated attackers can exploit this vulnerability over the network with low complexity and no user interaction. By controlling DNS resolution, an attacker can trick Vault into directing ACME challenge validation requests to attacker-specified local network targets, enabling server-side request forgery (SSRF). Successful exploitation leads to low-impact confidentiality violations, such as disclosure of sensitive information from internal services reachable via those local targets.
HashiCorp's security advisory, detailed in HCSEC-2026-06 on their discussion forum, confirms the SSRF vulnerability in ACME challenge validation and recommends upgrading to the patched versions: Vault Community Edition 2.0.0 or Vault Enterprise 2.0.0, 1.21.5, 1.20.10, and 1.19.16. No additional workarounds are specified in the available information.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-23344
Vulnerability details
Vault’s PKI engine’s ACME validation did not reject local targets when issuing http-01 and tls-alpn-01 challenges. This may lead to these requests being sent to local network targets, potentially leading to information disclosure. Fixed in Vault Community Edition 2.0.0 and…
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Vault Enterprise 2.0.0, 1.21.5, 1.20.10, and 1.19.16.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
SSRF vulnerability in public-facing HashiCorp Vault PKI/ACME service directly enables T1190 (Exploit Public-Facing Application) for unauthenticated remote information disclosure from internal/local targets.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Timely remediation through patching Vault to fixed versions (e.g., Community 2.0.0, Enterprise 2.0.0/1.21.5/1.20.10/1.19.16) directly eliminates the SSRF flaw in ACME validation.
Validates ACME challenge inputs to reject local network targets or resolutions, preventing Vault from issuing http-01/tls-alpn-01 requests to attacker-controlled internal destinations.
Monitors and controls Vault's outbound communications at key internal boundaries to block SSRF requests to local services and detect anomalous traffic patterns.