CVE-2026-5052

Medium

Published: 17 April 2026

Published

17 April 2026

Modified

27 April 2026

KEV Added

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Patch

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CVSS Score 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS Score 0.0001 3.1th percentile

Risk Priority 11 60% EPSS · 20% KEV · 20% CVSS

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 3.1th 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).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190). What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

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.

SI-10 Information Input Validation good match

prevent

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.

SC-7 Boundary Protection partial match

preventdetect

Monitors and controls Vault's outbound communications at key internal boundaries to block SSRF requests to local services and detect anomalous traffic patterns.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

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.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

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…

Vault Enterprise 2.0.0, 1.21.5, 1.20.10, and 1.19.16.

Deeper analysisAI

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.