# CVE-2026-105818 — HashiCorp Vault

> As of 2026-10-08, CVE-2026-105818 is a MEDIUM-severity vulnerability in HashiCorp Vault, CVSS v3.1 5.9, EPSS 0.0% (14.0th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-105818 as of 2026-10-08; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-10-08

## What is CVE-2026-105818?

Vault's PKI secrets engine ACME server did not restrict certificate identities that ACME challenges do not validate when issuing certificates under the default directory policy. This may allow an ACME client to obtain a certificate containing unverified identity claims, potentially enabling impersonation toward systems that trust certificates issued by the affected Vault PKI mount. This vulnerability (CVE-2026-105818) is fixed in Vault Community Edition 2.1.2, and Vault Enterprise 2.1.2, 1.21.12, 1.20.17, and 1.19.23.

The record classifies CVE-2026-105818 under weakness class [CWE-345](https://intel.threadlinqs.com/cwe/CWE-345). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on integrity. 2 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 3 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 5.9 — MEDIUM (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **EPSS (FIRST):** 0.0% probability of exploitation in the next 30 days, higher than 14.0% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-10-07, last modified 2026-10-08

## Is CVE-2026-105818 being exploited?

It currently carries a trending score of 33 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [HashiCorp](https://intel.threadlinqs.com/vendors/hashicorp): Vault, Vault Enterprise

## How to fix CVE-2026-105818

No vendor patch reference has been recorded for CVE-2026-105818 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-105818

No threat campaign in the Threadlinqs corpus currently references CVE-2026-105818, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-10-08. This product uses the NVD API but is not endorsed or certified by the NVD.

**Other references**

- [discuss.hashicorp.com](https://discuss.hashicorp.com/t/hcsec-2026-40-vault-pki-acme-default-directory-policy-may-issue-certificates-with-unverified-identities/77812)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-105818
Full detection coverage and IOCs for threats exploiting CVE-2026-105818 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp