How severe is CVE-2024-43398?

CVE-2024-43398 has a CVSS score of 5.9/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2024-43398?

CVE-2024-43398 affects the following packages: rexml (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2024-43398?

Update rexml to 3.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-43398 is resolved across your whole dependency graph.

How do I detect CVE-2024-43398 in my RubyGems dependencies?

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.

How do I mitigate CVE-2024-43398 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2024-43398 actively exploited in the wild?

No public exploit code has been indexed for CVE-2024-43398 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2024-43398?

CVE-2024-43398 has an EPSS (Exploit Prediction Scoring System) score of 1.2%, placing it in the 68th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2024-43398?

CVE-2024-43398 is classified as CWE-776 (CWE-776). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2024-43398 published, and has it been updated?

CVE-2024-43398 was published on August 22, 2024 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎

💎 RubyGems

Not in CISA KEV

MEDIUM severity

CVE-2024-43398 — rexml

MEDIUMFix: ruby/rexml@7cb5eae

CVE-2024-43398 is a medium-severity (CVSS 5.9) CWE-776 vulnerability in rexml. A fix is available for rexml — see the affected versions and patch details below.

REXML denial of service vulnerability

Also known asGHSA-vmwr-mc7x-5vc3

Published

Aug 22, 2024

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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-2024-43398.

EPSS Exploitation Probability

via FIRST.org ↗

1.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs68th percentile — riskier than 68% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

💎rexml

Real-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 3.3.6 has a DoS vulnerability when it parses an XML that has many deep elements that have same local name attributes.

If you need to parse untrusted XMLs with tree parser API like REXML::Document.new, you may be impacted to this vulnerability. If you use other parser APIs such as stream parser API and SAX2 parser API, this vulnerability is not affected.

Patches

The REXML gem 3.3.6 or later include the patch to fix the vulnerability.

Workarounds

Don't parse untrusted XMLs with tree parser API.

References

https://www.ruby-lang.org/en/news/2024/08/22/dos-rexml-cve-2024-43398/ : An announce on www.ruby-lang.org

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`rexml`	all versions	3.3.6`bundle update rexml --conservative`

Affected Products

2 products · 2 configurations

bootstrap osnetapp

all

Application

rexmlruby-lang

< 3.3.6

range

Detection & mitigation playbook

Open-source dependency

Detect
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 3.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-43398 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

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.

Red HatModerate

Moderate impact: Red Hat products in the current affected scope, including Red Hat Enterprise Linux and other products that ship the vulnerable REXML component, can be exposed to denial of service when an attacker supplies deeply nested XML with repeated local-name attributes to REXML's tree parser, such as…

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Source: Red Hat security advisory for CVE-2024-43398 (CC BY 4.0)

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 8	`pcs-0:0.10.18-2.el8_10.2`	RHSA-2024:6670
Red Hat Enterprise Linux 8.6 Telecommunications Update Service	`pcs-0:0.10.12-6.el8_6.6`	RHSA-2024:6702
Red Hat Enterprise Linux 8.8 Extended Update Support	`pcs-0:0.10.15-4.el8_8.3`	RHSA-2024:6703
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

### Impact The REXML gem before 3.3.6 has a DoS vulnerability when it parses an XML that has many deep elements that have same local name attributes. If you need to parse untrusted XMLs with tree parser API like `REXML::Document.new`, you may be impacted to this vulnerability. If you use other parser APIs such as stream parser API and SAX2 parser API, this vulnerability is not affected. ### Patches The REXML gem 3.3.6 or later include the patch to fix the vulnerability. ### Workarounds Don't parse untrusted XMLs with tree parser API. ### References * https://www.ruby-lang.org/en/news/2