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Pebble has Arbitrary Local File Inclusion (LFI) Vulnerability via `include` macro

High severity GitHub Reviewed Published Feb 24, 2025 in JLLeitschuh/security-research • Updated Feb 28, 2025

Package

maven io.pebbletemplates:pebble (Maven)

Affected versions

<= 3.2.3

Patched versions

None

Description

Summary

If untrusted user input is used to dynamically create a PebbleTemplate with the method PebbleEngine#getLiteralTemplate, then an attacker can include arbitrary local files from the file system into the generated template, leaking potentially sensitive information into the output of PebbleTemplate#evaluate. This is done via the include macro.

Details

The include macro calls PebbleTempateImpl#resolveRelativePath with the relativePath argument passed within the template:

Example template:

{% include [relativePath] %}

When resolveRelativePath is called, the relativePath is resolved against the PebbleTemplateImpl.name variable.

  /**
   * This method resolves the given relative path based on this template file path.
   *
   * @param relativePath the path which should be resolved.
   * @return the resolved path.
   */
  public String resolveRelativePath(String relativePath) {
    String resolved = this.engine.getLoader().resolveRelativePath(relativePath, this.name);
    if (resolved == null) {
      return relativePath;
    } else {
      return resolved;
    }
  }

https://github.com/PebbleTemplates/pebble/blob/82ad7fcf9e9eaa45ee82ae3335a1409d19c10263/pebble/src/main/java/io/pebbletemplates/pebble/template/PebbleTemplateImpl.java#L380

Unfortunately, when the template is created from a string, as is the case when PebbleEngine#getLiteralTemplate is used, the PebbleTemplateImpl.name variable is actually the entirety of the contents of the template, not a filename as the logic expects. The net result is that the relativePath is resolved against the system root directory. As a result, files accessible from the root directory of the filesystem can be included into a template.

PoC

The following test demonstrates the vulnerability:

PebbleEngine e = new PebbleEngine.Builder().build();

String templateString = """
        {% include '/etc/passwd' %}
        """;
PebbleTemplate template = e.getLiteralTemplate(templateString);

try (final Writer writer = new StringWriter()) {
    template.evaluate(writer, new HashMap<>());
    System.out.println(writer);
}

As an attacker, the following malicious template demonstrates the vulnerability:

{% include '/etc/passwd' %}

Impact

This is an arbitrary Local File Inclusion (LFI) vulnerability. It can allow attackers to exfiltrate the contents of the local filesystem, including sensitive files into PebbleTemplate output. This can also be used to access the /proc filesystem which can give an attacker access to environment variables.

Fix

There exists no published fix for this vulnerability. The best way to mitigate this vulnerability is to disable the include macro in Pebble Templates.

The following can safeguard your application from this vulnerability:

new PebbleEngine.Builder()
            .registerExtensionCustomizer(new DisallowExtensionCustomizerBuilder()
                    .disallowedTokenParserTags(List.of("include"))
                    .build())
            .build();

Report Timeline

Vulnerability was reported under the Open Source Security Foundation (OpenSSF) Model Outbound Vulnerability Disclosure Policy: Version 0.1.

  • Jul 15, 2024 Maintainer Contacted to enable private vulnerability reporting
  • Jul 18, 2024 I opened a GHSA
    to report this vulnerability to the maintainer https://github.com/PebbleTemplates/pebble/security/advisories/GHSA-7c6h-hmf9-7wj7 (private link)
  • Jul 29, 2024 GHSA updated to ping maintainer about vulnerability, no response
  • Oct 1, 2024 GHSA updated to ping maintainer about vulnerability, no response
  • Nov 15, 2024 GHSA updated to inform maintainer that disclosure timeline had lapsed, no response.
  • Feb 19, 2025 GHSA updated to inform maintainer that disclosure would occur imminently, no response.
  • Feb 24, 2025 this GHSA was created to disclose this vulnerability without a patch available.

For further discussion, see this issue: PebbleTemplates/pebble#688

Credit

This vulnerability was discovered by @JLLeitschuh while at Chainguard Labs. Jonathan is currently independent.

References

@JLLeitschuh JLLeitschuh published to JLLeitschuh/security-research Feb 24, 2025
Published by the National Vulnerability Database Feb 27, 2025
Published to the GitHub Advisory Database Feb 28, 2025
Reviewed Feb 28, 2025
Last updated Feb 28, 2025

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required High
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity High
Availability High
Subsequent System Impact Metrics
Confidentiality Low
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:H/SC:L/SI:N/SA:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(18th percentile)

Weaknesses

CVE ID

CVE-2025-1686

GHSA ID

GHSA-p75g-cxfj-7wrx

Source code

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