CVE-2021-25951Public exploitNetwork attack vector

Denial of service via recursive entity expansion

Published Jun 30, 2021 · Updated Aug 3, 2024

XML entity expansion in Sprint Mc XML2Dict 0.2.2 allows remote attackers to cause a service interruption via crafted XML. The parse function accepts recursive entity references in a document type definition and expands them without limits, exhausting processor time or memory. An application must pass attacker-controlled XML into the library; the demonstrated consequence is loss of availability rather than data access or modification.

CVSS severity7.5
High
EPSS probability1.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XML entity expansion in Sprint Mc XML2Dict 0.2.2 allows remote attackers to cause a service interruption via crafted XML. The parse function accepts recursive entity references in a document type definition and expands them without limits, exhausting processor time or memory. An application must pass attacker-controlled XML into the library; the demonstrated consequence is loss of availability rather than data access or modification.

The record

CVE
CVE-2021-25951
Published
Jun 30, 2021
Updated
Aug 3, 2024
Vendor
Sprint Mc
Product
XML2Dict
Classifications
CWE-611, CWE-776, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 30, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=0.2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Sprint Mc · XML2Dictversion=0.2.2

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
8.7GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA: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 exploitPublished

Weakness, pattern, technique

CWE-611Improper Restriction of XML External Entity Reference
CWE-776Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
T1499.002Service Exhaustion Flood

Public exploit references

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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