CVE-2021-1628Network attack vector

Remote XML entity abuse

Published Mar 26, 2021 · Updated Aug 3, 2024

XML external entity injection in Mule Runtime Engine 4.x before February 2, 2021 allows remote attackers to cause unspecified impact via crafted XML input. The vulnerable Mule runtime component parses attacker-controlled XML while permitting external entity resolution; the public record does not identify the exact parser locus or operation. Exploitation requires a reachable Mule application or flow that processes the crafted XML, and the bounded consequence can include local-file disclosure or outbound requests depending on configuration.

CVSS severity9.8
Critical
EPSS probability1.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XML external entity injection in Mule Runtime Engine 4.x before February 2, 2021 allows remote attackers to cause unspecified impact via crafted XML input. The vulnerable Mule runtime component parses attacker-controlled XML while permitting external entity resolution; the public record does not identify the exact parser locus or operation. Exploitation requires a reachable Mule application or flow that processes the crafted XML, and the bounded consequence can include local-file disclosure or outbound requests depending on configuration.

The record

CVE
CVE-2021-1628
Published
Mar 26, 2021
Updated
Aug 3, 2024
Vendor
Salesforce
Product
Mule Runtime Engine
Classifications
CWE-611, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 26, 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=Mule 4.x runtime released before February 2, 2021

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Salesforce · Mule Runtime Engineversion=Mule 4.x runtime released before February 2, 2021

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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
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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