CVE-2021-38555Network attack vector

File disclosure via external XML entity resolution

Published Sep 11, 2021 · Updated Aug 4, 2024

XXE injection in StreamUtils.java in Apache Any23 before 2.5 allows remote attackers to read server files through crafted XML. The utility creates an XML parser that accepts DTDs and resolves attacker-controlled external entity URIs instead of disabling external resource loading. Reachability requires an application, CLI invocation, or REST service to pass untrusted XML into the affected utility; the parser can also contact systems accessible to its host.

CVSS severity9.1
Critical
EPSS probability2.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XXE injection in StreamUtils.java in Apache Any23 before 2.5 allows remote attackers to read server files through crafted XML. The utility creates an XML parser that accepts DTDs and resolves attacker-controlled external entity URIs instead of disabling external resource loading. Reachability requires an application, CLI invocation, or REST service to pass untrusted XML into the affected utility; the parser can also contact systems accessible to its host.

The record

CVE
CVE-2021-38555
Published
Sep 11, 2021
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache Any23
Classifications
CWE-611, T1190, T1005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 11, 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?

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

  1. Affected versionversion=Apache Any23 <2.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Any23version=Apache Any23 <2.5

Published CVSS scores

9.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
6.4NIST National Vulnerability DatabaseAV: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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 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
T1190Exploit Public-Facing Application
T1005Data from Local System

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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