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consul-template CVE-2026-87993

| EUVDEUVD-2026-75701 HIGH
Insertion of Sensitive Information into Log File (CWE-532)
2026-09-10 HashiCorp GHSA-h4cr-56m4-rqc8
7.7
CVSS 3.1 · Vendor: HashiCorp
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Trigger consul-template rendering error (bad path/type)
  2. Delivery
    Error handler serializes Vault secret into error string
  3. Exploit
    Error emitted to Nomad task events and logs
  4. Execution
    Attacker reads task events with Nomad operator credentials
  5. Impact
    Vault secret value extracted from error output

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A09:2025 - Security Logging & Alerting Failures
ASVS 5.0
V16 - Security Logging and Error Handling Log data sanitization
Exploitation Conditions

Requires consul-template to be deployed in Vault integration mode (i.e., templates reference Vault secret paths via the secret or with secret template functions). A template rendering error must occur - caused by a misconfigured template, missing Vault path, wrong data type, or transient Vault unavailability. The attacker then needs read access to a downstream surface that receives the error output: Nomad task event history, a log aggregation system, or consul-template's stderr. PR:L (low privileges) reflects that Nomad operator-level access suffices to read task events. Exploitation is limited to deployments where consul-template is integrated with Vault; deployments using consul-template exclusively with Consul KV or environment variables are not affected by the Vault-secret disclosure aspect.

Impact

The vendor-supplied CVSS 7.7 (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N) is well-calibrated for this class of issue. PR:L correctly reflects that triggering or observing the error requires some operational access - a Nomad job submitter or operator with task-event read access fits this profile. The S:C (scope changed) metric captures the key real-world risk: Vault secrets intended to be ephemeral and privilege-gated instead persist in Nomad event history and log aggregation systems (e.g., Splunk, Elasticsearch) where retention policies and RBAC differ from Vault's own access controls. No public exploit code exists and the vulnerability is not in CISA KEV, making this a low-urgency but meaningful hygiene patch - particularly for organizations where Vault stores high-value secrets (database credentials, cloud API keys) and Nomad task events are accessible to a broader operator tier than Vault itself.

Exploit ScenarioDerived

A Nomad operator with job-submission privileges submits a job that uses a consul-template rendering a Vault KV secret path that contains a typo or refers to a missing secret. consul-template encounters a rendering error, serializes the resolved (but partial) Vault secret values into the error message, and Nomad records this error in the task events API. A second operator - with Nomad read access but without Vault policy grants for that secret - queries the Nomad task events and reads the Vault secret value in plain text from the error output. No public exploit code exists for this issue.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 10, 2026

Vault secret values leak into error messages, log output, and Nomad task events in HashiCorp consul-template due to improper error handling. The vulnerability affects consul-template deployments integrated with HashiCorp Vault, where a template rendering error can inadvertently expose secret values to any downstream surface that receives error text - including Nomad task event logs readable by lower-privileged operators. The scope-changed CVSS vector (S:C) reflects that the primary harm falls on systems outside consul-template itself: Vault secrets meant to be accessed only by privileged services instead persist in Nomad task events and logging infrastructure accessible to broader audiences.

RemediationAI

Upgrade consul-template to version 0.43.0 or later, as confirmed by the HashiCorp advisory at https://discuss.hashicorp.com/t/hcsec-2026-38-consul-template-vulnerable-to-an-information-disclosure-issue-in-error-handling/77740. If an immediate upgrade is not possible, restrict read access to Nomad task events and structured logs to only those principals who already have equivalent Vault access - this reduces the blast radius by aligning log visibility with Vault policy. Additionally, enable Vault audit logging to detect any secret values that may have already leaked into log streams and rotate credentials for secrets associated with templates that have historically produced rendering errors. Note that restricting log access is a compensating control only; it does not prevent the secrets from being written to logs in the first place.

Affected VersionsENISA

Tooling 0.27.2 <0.43.0

Affected Packages

euvd tooling fix: 0.43.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

consul-template is HashiCorp's daemon that watches Vault (and Consul/Nomad) for data changes and dynamically renders configuration templates. CWE-532 (Insertion of Sensitive Information into Log File) describes the root cause: when the template rendering pipeline encounters an error - such as a missing Vault path, type mismatch, or malformed template - the error handler serializes the rendering context including resolved Vault secret values into the error string, which is then emitted to stderr, structured logs, and Nomad's task event API. The CPE supplied (cpe:2.3:a:hashicorp:tooling:*:*:*:*:*:*:*:*) is a generic placeholder; the actual affected product is the hashicorp/consul-template binary and library, fixed at version 0.43.0.

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Severity by source

Vendor (HashiCorp) PRIMARY 7.7 HIGH
AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
vuln.today AI 7.7 HIGH

PR:L reflects Nomad operator access needed to trigger or read errors; S:C because Vault secrets escape into Nomad and log systems outside consul-template's security scope.

3.1 AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N

Primary rating from Vendor (HashiCorp).

CVSS VectorVendor: HashiCorp

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

Lifecycle Timeline

2
Patch available
Sep 10, 2026 - 21:02 EUVD
CVE Published
Sep 10, 2026 - 19:00 cve.org
HIGH 7.7

DescriptionCVE.org

The consul-template library is vulnerable to an information disclosure issue in its error handling path that may allow Vault secret values to appear in template error messages, log output, and downstream surfaces such as Nomad task events. This vulnerability (CVE-2026-87993) is fixed in consul-template 0.43.0.

Executive ViewAI

Why It Matters

HashiCorp consul-template exposes Vault secrets in error logs and Nomad task events, allowing lower-privileged infrastructure operators to access credentials intended only for privileged services. For organizations running Vault with Nomad orchestration, this creates a privilege escalation path that compromises all secrets stored in Vault. Rapid inventory and remediation is required to prevent credential theft and lateral movement.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: restrict RBAC access to Nomad task event logs to administrators only; implement log redaction or filtering to mask error messages containing secrets; rotate Vault secrets currently exposed; increase Vault audit logging to detect unauthorized credential usage; consider isolating consul-template in containers with restricted log output; disable error logging if the application supports alternative error handling.

Threat Intelligence Overview

EPSS Score
0.3%
Top 80% exploitable
Prevalence
Medium
popular in HashiCorp Vault/Nomad/Consul enterprise stacks
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Partial

Priority Score

38
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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