CVE-2024-39908 — rexml
MEDIUMCVE-2024-39908 is a medium-severity (CVSS 4.3) Uncontrolled Resource Consumption vulnerability in rexml. A fix is available for rexml — see the affected versions and patch details below.
Denial of service in REXML
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-39908.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2024-39908 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
rexmlReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rexml | all versions | 3.3.2bundle update rexml --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rexml, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rexml to 3.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-39908 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-39908 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-39908. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 8 | ruby:3.3-8100020240906074654.489197e6 | RHSA-2024:6784 |
| Red Hat Enterprise Linux 8 | ruby:3.1-8100020250407112943.489197e6 | RHSA-2025:4063 |
| Red Hat Enterprise Linux 9 | ruby:3.3-9040020240906110954.9 | RHSA-2024:6785 |
| Red Hat Enterprise Linux 9 | ruby:3.1-9050020250404144903.9 | RHSA-2025:4488 |
Frequently Asked Questions
Is CVE-2024-39908 in your dependencies?
O3 Security finds CVE-2024-39908 across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.