GHSA-w5r2-gvgf-mpm8 CVE-2019-12463
Improper Encoding or Escaping of Output and Injection in LibreNMS
- Severity
- 8.8 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 1.39%
- Chance of exploitation in the next 30 days. Higher than 72.37% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-116 Improper Encoding or Escaping of Output
- CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
- Fix
1.53- Upgrade librenms/librenms to this version or later
Description
An issue was discovered in LibreNMS 1.50.1. The scripts that handle graphing options (includes/html/graphs/common.inc.php and includes/html/graphs/graphs.inc.php) do not sufficiently validate or encode several fields of user supplied input. Some parameters are filtered with mysqli_real_escape_string, which is only useful for preventing SQL injection attacks; other parameters are unfiltered. This allows an attacker to inject RRDtool syntax with newline characters via the html/graph.php and html/graph-realtime.php scripts. RRDtool syntax is quite versatile and an attacker could leverage this to perform a number of attacks, including disclosing directory structure and filenames, disclosing file content, denial of service, or writing arbitrary files. NOTE, relative to CVE-2019-10665, this requires authentication and the pathnames differ.
Affected versions
Packagist
| Package | Vulnerable | Fixed in |
|---|---|---|
| librenms/librenms | >= 1.50.1, < 1.53 |
1.53 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
librenms/librenms Packagist → 1.53
- composer
composer require librenms/librenms:^1.53
Severity breakdown
CVSS 3.1 8.8
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-116: Improper Encoding or Escaping of Output
The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
How to prevent it
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using the ESAPI Encoding control [REF-45] or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error. Alternately, use built-in functions, but consider using wrappers in case those functions are discovered to have a vulnerability.
- Architecture and Design: If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated. For example, stored procedures can enforce database query structure and reduce the likelihood of SQL injection.
- Architecture and Design, Implementation: Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
- Architecture and Design: In some cases, input validation may be an important strategy when output encoding is not a complete solution. For example, you may be providing the same output that will be processed by multiple consumers that use different encodings or representations. In other cases, you may be required to allow user-supplied input to contain control information, such as limited HTML tags that support formatting in a wiki or bulletin board. When this type of requirement must be met, use an extremely strict allowlist to limit which control sequences can be used. Verify that the resulting syntactic structure is what you expect. Use your normal encoding methods for the remainder of the input.
- Architecture and Design: Use input validation as a defense-in-depth measure to reduce the likelihood of output encoding errors (see CWE-20).
- Requirements: Fully specify which encodings are required by components that will be communicating with each other.
- Implementation: When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.
How to prevent it
- Requirements: Programming languages and supporting technologies might be chosen which are not subject to these issues.
- Implementation: Utilize an appropriate mix of allowlist and denylist parsing to filter control-plane syntax from all input.
References
Advisories
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-7w8c-qgxg-m7jx LibreNMS — Stored XSS via SNMP/Syslog Data in Legacy Templates | High | Also affects librenms/librenms |
| GHSA-7gww-x7fh-jf9j LibreNMS: SSRF-driven stored XSS via Oxidized API response fields in device showconfig page | Critical | Also affects librenms/librenms |
| GHSA-7cj5-v4pp-v632 LibreNMS: Stored XSS via graph_descr admin config settings echoed without escaping to all authenticated users | Medium | Also affects librenms/librenms |
| GHSA-jf24-8g2h-2wg7 LibreNMS Vulnerable to Remote Code Execution via AboutController | High | Also affects librenms/librenms |
| GHSA-c9fv-cgmm-2wg7 LibreNMS Vulnerable to Remote Code Execution by Signal Alert Transportation module | High | Also affects librenms/librenms |
| GHSA-jmqm-f8q4-v7wx LibreNMS: Reflected XSS via Proxmox instance/vmid GET parameters injected into document.title JavaScript assignment | Medium | Also affects librenms/librenms |
| GHSA-5gm9-622f-qcg5 LibreNMS: Cross-Site Scripting in ShowConfigController | Medium | Also affects librenms/librenms |
| GHSA-pr3g-phhr-h8fh LibreNMS is Vulnerable to Remote Code Execution by Arbitrary File Write | High | Also affects librenms/librenms |
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