CVE-2024-49761 — rexml
Fix: ruby/rexml@ce59f2eCVE-2024-49761 is a CWE-1333 vulnerability in rexml. A fix is available for rexml — see the affected versions and patch details below.
REXML ReDoS vulnerability
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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-2024-49761.
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.
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
Impact
The REXML gem before 3.3.9 has a ReDoS vulnerability when it parses an XML that has many digits between &# and x...; in a hex numeric character reference (&#x...;).
This does not happen with Ruby 3.2 or later. Ruby 3.1 is the only affected maintained Ruby. Note that Ruby 3.1 will reach EOL on 2025-03.
Patches
The REXML gem 3.3.9 or later include the patch to fix the vulnerability.
Workarounds
Use Ruby 3.2 or later instead of Ruby 3.1.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rexml | all versions | 3.3.9bundle 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 3.3.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-49761 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-2024-49761 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-49761. 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.
This vulnerability is rated as a moderate severity because it allows attackers to exploit inefficient regex parsing in hex numeric character references (&#x...;), causing a ReDoS and impacting availability, it requires specific malicious input but does not affect confidentiality or integrity. Satellite employs…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 8 | ruby:3.1-8100020241127152928.489197e6 | RHSA-2024:10834 |
| Red Hat Enterprise Linux 8 | ruby:2.5-8100020241127152844.489197e6 | RHSA-2024:10850 |
| Red Hat Enterprise Linux 8 | pcs-0:0.10.18-2.el8_10.6 | RHSA-2025:11047 |
| Red Hat Enterprise Linux 8.2 Advanced Update Support | ruby:2.5-8020020241211125628.4cda2c84 | RHSA-2024:11027 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | ruby:2.5-8040020241211104816.522a0ee4 | RHSA-2024:11028 |
| Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | ruby:2.5-8060020241211101132.ad008a3a | RHSA-2024:11029 |
| Red Hat Enterprise Linux 8.6 Telecommunications Update Service | pcs-0:0.10.12-6.el8_6.9 | RHSA-2025:13307 |
| Red Hat Enterprise Linux 8.8 Extended Update Support | ruby:3.1-8080020241210144941.63b34585 | RHSA-2024:10966 |
Frequently Asked Questions
Is CVE-2024-49761 in your dependencies?
O3 Security finds CVE-2024-49761 across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.