CVE-2026-12544

Executive Summary

CVE-2026-12544 is a code flaw in the Foreman lifecycle management platform, specifically within the foreman-rake initialization logic located at /usr/share/foreman/config/settings.rb. The vulnerable pattern processes configuration data through two distinct executable layers, creating a multi-stage execution chain that enables Server-Side Template Injection (SSTI) and insecure deserialization, both of which can culminate in remote code execution. With a CVSS base score of 7.7 (High) under a scope-changed vector, successful exploitation can lead to total infrastructure compromise and downstream supply chain risk for organizations using Foreman to manage fleets of hosts.

Technical Analysis

The core issue is classified under CWE-502 (Deserialization of Untrusted Data), and the NVD description states the flaw resides in the foreman-rake initialization logic housed at /usr/share/foreman/config/settings.rb. According to the description, configuration data is passed through two distinct executable layers, forming a multi-stage execution chain. This design permits two overlapping vulnerability classes to be triggered:

1. Server-Side Template Injection (SSTI) — configuration data that reaches a template rendering engine without proper sanitization can be interpreted as executable template directives rather than inert values.
2. Insecure deserialization — serialized configuration data that is reconstructed into live objects without integrity or type validation can be abused to instantiate attacker-controlled objects that execute code upon deserialization.

The combination of these two layers is significant because each layer independently widens the attack surface. The first executable layer may render or transform configuration content, and the second layer reconstructs or evaluates it, creating a chained execution path. Because foreman-rake is an administrative initialization and task utility, data flowing into this path is by design trusted and lower in sanitization, which is precisely what makes the pattern dangerous: a privileged configuration surface is being consumed by executable logic.

The CVSS vector CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H is informative about the exposure profile:

• AV:L (Local) — the attack vector is local, indicating the attacker must already have some form of local access or the ability to influence a local configuration file/process.
• AC:L (Low) — no special attack complexity is required once the precondition is met.
• PR:H (High) — the attacker requires high privileges, consistent with the fact that foreman-rake and /usr/share/foreman/config/settings.rb are administrative artifacts.
• UI:R (User Interaction Required) — a user (likely an administrator) must trigger the initialization logic for exploitation to occur.
• S:C (Scope Changed) — the impact crosses a trust boundary, so the vulnerable component's compromise can affect resources beyond its own security scope.
• C:H / I:H / A:H — full compromise of confidentiality, integrity, and availability.

Specific function names, serialization formats, template engine identifiers, and parameter names are not disclosed in the available NVD description. Per accuracy constraints, they are not fabricated here. The attack mechanism is therefore described at the vulnerability-class level: a two-layer executable configuration pipeline that evaluates untrusted input as code and/or deserializes untrusted input into live objects.

Exploitation Scenarios

No public proof-of-concept, Nuclei template, or exploit code is available for CVE-2026-12544 as of this writing. The following attack chain is inferred strictly from the vulnerability class and the details present in the NVD description.

1) Reconnaissance / target identification. The attacker identifies a Foreman deployment running the affected foreman-rake initialization logic. Because the vector is local and privileges are high, the realistic adversary is an insider, a compromised administrative account, or an attacker who has already achieved local foothold on the Foreman host and can influence configuration content consumed by /usr/share/foreman/config/settings.rb.

2) Triggering the flaw class. The attacker supplies crafted configuration data that flows through the two distinct executable layers described in the NVD entry. In the SSTI path, the crafted value is interpreted as template directives during rendering. In the insecure deserialization path, the crafted value is reconstructed into an object graph without validation.

3) Payload / execution method. Depending on which of the two layers is reached first, the attacker either injects template expressions that evaluate to executable code, or supplies a serialized object that invokes a dangerous method chain upon deserialization. In both cases the outcome is code execution in the context of the foreman-rake process.

4) Post-exploitation impact. Because Foreman is an infrastructure lifecycle management platform, code execution within its administrative context provides access to managed hosts, credentials, and provisioning data. The NVD entry explicitly cites total infrastructure compromise and supply chain risk, meaning the attacker can pivot from the management plane to the managed fleet.

Impact Assessment

With CVSS 7.7 (High) and a scope-changed vector, the impact extends beyond the directly vulnerable component. A compromise of Foreman's initialization path does not merely affect the Foreman server; because Foreman orchestrates host provisioning, configuration management, and often holds credentials and certificates for downstream systems, the blast radius includes every managed host and any integrated supply chain pipeline. The High integrity rating (I:H) means an attacker could alter provisioning templates, host configurations, or distribution content, which is the mechanism behind the cited supply chain risk. The High availability rating (A:H) means disruption of the management plane can cascade to managed infrastructure. The Scope Changed (S:C) rating confirms that the security authority of the vulnerable component is not sufficient to contain the impact. No EPSS score has been issued by FIRST.org, no CISA KEV listing exists, and there is no evidence of active exploitation in the wild as of this writing. The primary risk driver is not mass exploitation but the severity of impact for organizations running Foreman in a privileged role.

Detection Guidance

Sigma Rule

title: Foreman foreman-rake Initialization SSTI and Deserialization Exploitation Attempt
id: 8f3c2a91-7d4e-4b10-9c6a-2f1e5d8b7a44
status: experimental
description: Detects suspicious invocation or manipulation of foreman-rake initialization logic related to CVE-2026-12544
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-12544
author: Valters IT Threat Intelligence
date: 2026/01/01
tags:
  - attack.t1059
  - attack.t1190
logsource:
  category: process_creation
  product: linux
detection:
  selection_bin:
    Image|endswith:
      - '/foreman-rake'
      - '/rake'
  selection_path:
    CommandLine|contains:
      - 'settings.rb'
      - '/usr/share/foreman/config/'
  selection_suspicious:
    CommandLine|contains:
      - 'eval'
      - 'Marshal.load'
      - 'YAML.load'
      - '<%'
      - '${'
  condition: selection_bin and (selection_path or selection_suspicious)
falsepositives:
  - Legitimate administrator-initiated foreman-rake maintenance tasks
level: high

YARA Rule

rule CVE_2026_12544_Foreman_Rake_SSTI_Deserialization
{
    meta:
        description = "Detects suspicious template or serialization markers in Foreman settings.rb and rake initialization artifacts"
        author = "Valters IT Threat Intelligence"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-12544"
        date = "2026-01-01"
        cve = "CVE-2026-12544"

    strings:
        $path = "/usr/share/foreman/config/settings.rb" ascii
        $ssti1 = "<%" ascii
        $ssti2 = "%>" ascii
        $ssti3 = "${" ascii
        $ser1 = "Marshal.load" ascii
        $ser2 = "YAML.load" ascii
        $ser3 = "Psych.load" ascii
        $rake = "foreman-rake" ascii

    condition:
        ($path and any of ($ssti*)) or
        ($rake and ($ser1 or $ser2 or $ser3)) or
        (2 of them)
}

Suricata IDS Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-12544 Foreman SSTI/Deserialization Payload in Request"; flow:to_server,established; content:"foreman"; http_uri; nocase; content:"<%"; http_client_body; content:"%>"; http_client_body; reference:cve,2026-12544; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-12544; classtype:attempted-admin; sid:2026125440; rev:1;)
alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-12544 Foreman Deserialization Marker in Request"; flow:to_server,established; content:"foreman"; http_uri; nocase; content:"Marshal"; http_client_body; content:"load"; http_client_body; reference:cve,2026-12544; classtype:attempted-admin; sid:2026125441; rev:1;)

Elastic Detection

process where process.name in ("foreman-rake", "rake", "ruby") and
process.command_line like~ "*settings.rb*" and
(process.command_line like~ "*eval*" or
 process.command_line like~ "*Marshal.load*" or
 process.command_line like~ "*YAML.load*" or
 process.command_line like~ "*<\%*")

Splunk SPL Query

index=linux sourcetype=linux_secure OR sourcetype=auditd (process_name="foreman-rake" OR process_name="rake" OR process_name="ruby")
| search (process="/usr/share/foreman/config/settings.rb" OR command_line="*settings.rb*")
| search (command_line="*eval*" OR command_line="*Marshal.load*" OR command_line="*YAML.load*" OR command_line="*<%*")
| stats count min(_time) as first_seen max(_time) as last_seen by host user process_name command_line
| sort - last_seen

Wazuh OSSEC Rule

<group name="foreman,cve-2026-12544,">
  <rule id="100544" level="12">
    <decoded_as>json</decoded_as>
    <field name="process.name">foreman-rake|rake|ruby</field>
    <match>settings.rb</match>
    <regex type="pcre2">(Marshal\.load|YAML\.load|Psych\.load|eval|<%)</regex>
    <description>CVE-2026-12544: Suspicious foreman-rake initialization with SSTI/deserialization markers</description>
    <mitre>
      <id>T1059</id>
    </mitre>
    <group>cve_2026_12544,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence is 2/4 — a single source (NVD) claims a patch, and that claim has not been independently confirmed. No vendor fix text, workaround, or affected version range was provided in the available data.

1. Immediate mitigations. Restrict local access to the Foreman host and to /usr/share/foreman/config/settings.rb and the foreman-rake initialization path to the smallest possible set of administrators, consistent with the PR:H rating. Audit who currently holds the ability to influence configuration data consumed by the initialization logic, and treat any such account as privileged. Avoid feeding externally sourced or untrusted values into foreman-rake initialization or configuration.

2. Patch / upgrade steps. Because patch details are claimed but unconfirmed, verify directly with the Foreman project's official security advisories and release notes before relying on any specific version. Do not assume a fixed version without an authoritative vendor confirmation. Where an official advisory is available, apply the vendor-recommended version and validate the fix in a staging environment before production rollout.

3. Long-term hardening. Enforce least privilege around all administrative initialization tooling. Avoid configuration pipelines that pass data through executable/templating layers where values could be interpreted as code or deserialized into live objects. Where deserialization of configuration is unavoidable, prefer safe deserialization modes and schema validation. Monitor the initialization path with the detection rules above and review changes to /usr/share/foreman/config/settings.rb under file integrity monitoring.

References

• NVD — CVE-2026-12544: https://nvd.nist.gov/vuln/detail/CVE-2026-12544
• CWE-502 (Deserialization of Untrusted Data): https://cwe.mitre.org/data/definitions/502.html
• MITRE ATT&CK T1059 (Command and Scripting Interpreter): https://attack.mitre.org/techniques/T1059/
• Foreman project security advisories: https://theforeman.org/security.html
• CISA KEV Catalog (CVE-2026-12544 not listed as of this writing): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

No public exploit code, Nuclei template, or evidence of active exploitation in the wild was identified for CVE-2026-12544 at the time of writing. No threat actor campaign has been associated with this CVE in the available data.