GHSA-m37g-mwcg-7j7v BIT-moodle-2021-40694 CVE-2021-40694
Moodle Improper Encoding or Escaping of Output
Medium
Packagist
- Severity
- 4.9 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.90%
- Chance of exploitation in the next 30 days. Higher than 59.71% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-116 Improper Encoding or Escaping of Output
- Fix
3.9.10- Upgrade moodle/moodle to this version or later
Description
Insufficient escaping of the LaTeX preamble made it possible for site administrators to read files available to the HTTP server system account.
Affected versions
Packagist
| Package | Vulnerable | Fixed in |
|---|---|---|
| moodle/moodle | >= 3.9, < 3.9.10 |
3.9.10 |
| moodle/moodle | >= 3.10, < 3.10.7 |
3.10.7 |
| moodle/moodle | >= 3.11, < 3.11.3 |
3.11.3 |
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.
moodle/moodle Packagist → 3.9.10
- composer
composer require moodle/moodle:^3.9.10
Severity breakdown
CVSS 3.1 4.9
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
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.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-cg8j-5cr2-568q Moodle TeX formula editor is vulnerable to DoS through lack of execution time limits | Medium | Also affects moodle/moodle |
| GHSA-ggxq-2mg9-8966 Moodle has a Remote Code Execution risk via file restore | High | Also affects moodle/moodle |
| GHSA-8jrv-wx83-w3xj Moodle Inserts Sensitive Information Into Sent Data | Medium | Also affects moodle/moodle |
| GHSA-hcm6-q6pc-xfhm Moodle has an authorization logic flaw | Critical | Also affects moodle/moodle |
| GHSA-vwhw-vp9v-q9c9 Moodle vulnerable to Cross-site Scripting | Medium | Also affects moodle/moodle |
| GHSA-5cx4-w4fh-fr57 Moodle Affected by Improper Restriction of Excessive Authentication Attempts | High | Also affects moodle/moodle |
| GHSA-qv78-6gpp-hm68 Moodle Open Redirect vulnerability | Medium | Also affects moodle/moodle |
| GHSA-qfh6-h7j6-fvjv Moodle formula injection vulnerability | High | Also affects moodle/moodle |
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