REXML is an XML toolkit for Ruby. The REXML gem before 3.3.1 has some DoS vulnerabilities when it parses an XML that has many specific characters such as <, 0 and %>. If you need to parse untrusted XMLs, you many be impacted to these vulnerabilities. The REXML gem 3.3.2 or later include the patches to fix these vulnerabilities. Users are advised to upgrade. Users unable to upgrade should avoid parsing untrusted XML strings.
Weakness
The product does not properly control the allocation and maintenance of a limited resource.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Rexml | Ruby-lang | * | 3.3.2 (excluding) |
| Red Hat Enterprise Linux 8 | RedHat | ruby:3.3-8100020240906074654.489197e6 | * |
| Red Hat Enterprise Linux 8 | RedHat | ruby:3.1-8100020250407112943.489197e6 | * |
| Red Hat Enterprise Linux 9 | RedHat | ruby:3.3-9040020240906110954.9 | * |
| Red Hat Enterprise Linux 9 | RedHat | ruby:3.1-9050020250404144903.9 | * |
| Jruby | Ubuntu | focal | * |
| Jruby | Ubuntu | oracular | * |
| Jruby | Ubuntu | plucky | * |
| Jruby | Ubuntu | trusty/esm | * |
| Ruby2.3 | Ubuntu | esm-infra/xenial | * |
| Ruby2.5 | Ubuntu | esm-infra/bionic | * |
| Ruby2.7 | Ubuntu | esm-infra/focal | * |
| Ruby2.7 | Ubuntu | focal | * |
| Ruby3.0 | Ubuntu | jammy | * |
| Ruby3.2 | Ubuntu | noble | * |
| Ruby3.3 | Ubuntu | oracular | * |
Potential Mitigations
Mitigation of resource exhaustion attacks requires that the target system either:
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.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/147.html
- https://cwe.mitre.org/data/definitions/227.html
- https://cwe.mitre.org/data/definitions/492.html
References
- https://github.com/ruby/rexml/security/advisories/GHSA-4xqq-m2hx-25v8
- https://www.ruby-lang.org/en/news/2024/07/16/dos-rexml-cve-2024-39908
- https://github.com/ruby/rexml/security/advisories/GHSA-4xqq-m2hx-25v8
- https://lists.debian.org/debian-lts-announce/2025/01/msg00011.html
- https://security.netapp.com/advisory/ntap-20250117-0008/
- https://www.ruby-lang.org/en/news/2024/07/16/dos-rexml-cve-2024-39908