CVE-2021-23901Network attack vector

File disclosure and backend access via external entities

Published Jan 25, 2021 · Updated Feb 13, 2025

XXE in Apache Nutch 1.17 and earlier allows context-dependent attackers to read local files or reach back-end systems via crafted DMOZ RDF. DmozParser passes the supplied RDF into a Xerces-backed SAX parser whose external-entity restrictions are insufficient, so entity references can resolve resources outside the intended XML data. Exploitation requires crafted XML to be processed by the DmozParser tool; the bounded consequence is file disclosure or requests to systems reachable from the crawler.

CVSS severity9.1
Critical
EPSS probability4.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XXE in Apache Nutch 1.17 and earlier allows context-dependent attackers to read local files or reach back-end systems via crafted DMOZ RDF. DmozParser passes the supplied RDF into a Xerces-backed SAX parser whose external-entity restrictions are insufficient, so entity references can resolve resources outside the intended XML data. Exploitation requires crafted XML to be processed by the DmozParser tool; the bounded consequence is file disclosure or requests to systems reachable from the crawler.

The record

CVE
CVE-2021-23901
Published
Jan 25, 2021
Updated
Feb 13, 2025
Vendor
The Apache Software Foundation
Product
Apache Nutch
Classifications
CWE-611, CAPEC-221, T1005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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=Apache Nutch <=1.17

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Nutchversion=Apache Nutch <=1.17

Published CVSS scores

9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
6.4NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-611Improper Restriction of XML External Entity Reference
CAPEC-221Data Serialization External Entities Blowup
T1005Data from Local System

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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