CVE-2021-44556Network attack vector

File disclosure and service interruption via external entities

Published Dec 8, 2021 · Updated Aug 4, 2024

XXE in KBNLresearch digger allows remote attackers to read local files or interrupt service through a malicious XML response. The ocr_to_dict path fetches the supplied URL and passes its response to lxml.etree.fromstring with an XMLParser that leaves external entity resolution enabled. The unauthenticated HTTP route must fetch an attacker-controlled URL; successful exploitation exposes server files or exhausts parser resources.

CVSS severity9.1
Critical
EPSS probability1.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XXE in KBNLresearch digger allows remote attackers to read local files or interrupt service through a malicious XML response. The ocr_to_dict path fetches the supplied URL and passes its response to lxml.etree.fromstring with an XMLParser that leaves external entity resolution enabled. The unauthenticated HTTP route must fetch an attacker-controlled URL; successful exploitation exposes server files or exhausts parser resources.

The record

CVE
CVE-2021-44556
Published
Dec 8, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-611, CAPEC-221, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

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

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
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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