GHSA-273w-7fxj-pcp6 BIT-moodle-2021-36395 CVE-2021-36395
Moodle vulnerable to Uncontrolled Resource Consumption
High
Packagist
- Severity
- 7.5 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.73%
- Chance of exploitation in the next 30 days. Higher than 54.41% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Fix
3.11.1- Upgrade moodle/moodle to this version or later
Description
In Moodle, the file repository's URL parsing required additional recursion handling to mitigate the risk of recursion denial of service.
Affected versions
Packagist
| Package | Vulnerable | Fixed in |
|---|---|---|
| moodle/moodle | >= 3.11.0-beta, < 3.11.1 |
3.11.1 |
| moodle/moodle | >= 3.10.0-beta, < 3.10.5 |
3.10.5 |
| moodle/moodle | < 3.9.8 |
3.9.8 |
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 → 3.11.1
- composer
composer require moodle/moodle:^3.11.1
Severity breakdown
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
CWE-400: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How to prevent it
- Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
- Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
- Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
- Implementation: Ensure that all failures in resource allocation place the system into a safe posture.
CWE-674: Uncontrolled Recursion
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
How to prevent it
- Implementation: Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
- Implementation: Increase the stack size.
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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