CVE-2024-43398Network attack vector

Application hang via repeated namespace resolution

Published Aug 22, 2024 · Updated Nov 3, 2025

Denial of service in REXML before 3.3.6 allows remote attackers to hang applications by supplying deeply nested XML to the tree parser. The tree parser defers duplicate expanded-name checks to element construction, repeatedly resolving namespaces for same-local-name attributes as nesting grows. Only applications that pass untrusted XML to tree APIs such as REXML::Document.new are exposed; stream and SAX2 parsers are unaffected.

CVSS severity5.9
Medium
EPSS probability1.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in REXML before 3.3.6 allows remote attackers to hang applications by supplying deeply nested XML to the tree parser. The tree parser defers duplicate expanded-name checks to element construction, repeatedly resolving namespaces for same-local-name attributes as nesting grows. Only applications that pass untrusted XML to tree APIs such as REXML::Document.new are exposed; stream and SAX2 parsers are unaffected.

The record

CVE
CVE-2024-43398
Published
Aug 22, 2024
Updated
Nov 3, 2025
Vendor
libwww-perl
Product
REXML
Classifications
CWE-776, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 22, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.3.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

libwww-perl · REXMLversion=< 3.3.6

Published CVSS scores

5.9GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-776Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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