BlackTreeCVE Intelligence
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Full vulnerability report · 2021
CVE-2021-21829High confidence

A heap-based buffer overflow vulnerability exists in the XML Decompression EnumerationUncompressor::UncompressItem functionality of AT&T Labs’ Xmill 0.7

n/a · AT&T

9.8CriticalCVSS 3.1
Recommended action
Within 72 hours

Critical technical impact with a remotely reachable, unauthenticated path and a public exploit reference; no CISA KEV confirmation is currently recorded.

Patch available
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
SEVD-2021-222-02 · CSAF 2.0 · revision 4.0.0 · finalSchneider Electric CPCERTAT&T Labs Compressor (XMilI) and Decompressor (XDemill) used by EcoStruxureTM Control Expert, EcoStruxureTM Process Expert and SCADAPack RemoteConnect™ for x70
3 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • Schneider Electric EcoStruxure™ Control Expert <15.1 HF001
  • Schneider Electric EcoStruxure™ Process Expert <2021
  • Schneider Electric SCADAPack RemoteConnect™ for x70 <R2.7.3
Summary
The vulnerabilities reported on XDemill and XMilI are triggered through the execution of a malicious script on the engineering workstation, or when loading a specially crafted project file into the engineering tool. The successful exploitation of these vulnerabilities may lead to code execution with elevated privileges on the engineering workstation.
Remediation
V15.1 HF001 of EcoStruxure™ Control Expert includes a fix for these vulnerabilities and is available for download here: https://www.se.com/ww/en/download/document/ControlExpert_V151_HF001/ If customers choose not to apply the remediation provided above, they should immediately apply the following mitigations to reduce the risk of exploit: • Store the project files in a secure storage and restrict the access to only trusted users • When exchanging files over the network, use secure communication channels • Only open project files received from a trusted source • Compute a hash of the project files and regularly check the consistency of this hash to verify the integrity before usage • Harden the workstation running EcoStruxure Control Expert or Unity Pro • Customers using Unity Pro should strongly consider migrating to EcoStruxure Control Expert.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-9000

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 72 hours

Critical technical impact with a remotely reachable, unauthenticated path and a public exploit reference; no CISA KEV confirmation is currently recorded.

Patch available
01

What, why and how

A heap-based buffer overflow vulnerability exists in the XML Decompression EnumerationUncompressor::UncompressItem functionality of AT&T Labs’ Xmill 0.7. A specially crafted XMI file can lead to remote code execution. An attacker can provide a malicious file to trigger this vulnerability.

What

A heap-based buffer overflow vulnerability exists in the XML Decompression EnumerationUncompressor::UncompressItem functionality of AT&T Labs’ Xmill 0.7. A specially crafted XMI file can lead to remote code execution. An attacker can provide a malicious file to trigger this vulnerability.

Why

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

What

A heap-based buffer overflow vulnerability exists in the XML Decompression EnumerationUncompressor::UncompressItem functionality of AT&T Labs’ Xmill 0.7. A specially crafted XMI file can lead to remote code execution. An attacker can provide a malicious file to trigger this vulnerability.

Why

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Heap-based Buffer Overflow → execute code or commands in the affected security context
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-122 ↗

CWE-122: Heap-based Buffer Overflow. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
NetworkUnauthenticatedRemote code executionCWE-122Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

CERT-FR · French · CERTFR-2022-AVI-646Multiples vulnérabilités dans les produits Schneider Electric

d?id=CVE-2021-21811 Référence CVE CVE-2021-21812 https://www.cve.org/CVERecord?id=CVE-2021-21812 Référence CVE CVE-2021-21813 https://www.cve.org/CVERecord?id=CVE-2021-21813 Référence CVE CVE-2021-21814 https://www.cve.org/CVERecord?id=CVE-2021-21814 Référence CVE CVE-2021-21815 https://www.cve.org/CVERecord?id=CVE-2021-21815 Référence CVE CVE-2021-21825 https://www.cve.org/CVERecord?id=CVE-2021-21825 Référence CVE CVE-2021-21826 https://www.cve.org/CVERecord?id=CVE-2021-21826 Référence CVE CVE-2021-21827 https://www.cve.org/CVERecord?id=CVE-2021-21827 Référence CVE CVE-2021-21828 https://www.cve.org/CVERecord?id=CVE-2021-21828 Référence CVE CVE-2021-21829 https://www.cve.org/CVERecord?id=CVE-2021-21829 Référence CVE CVE-2021-21830 https://www.cve.org/CVERecord?id=CVE-2021-21830 Référence CVE CVE-2021-22797 https://www.cve.org/CVERecord?id=CVE-2021-22797 Référence CVE CVE-2022-26507 https://www.cve.org/CVERecord?id=CVE-2022-26507 Référence CVE CVE-2022-34759 https://www.cve.org/CVERecord?id=CVE-2022-34759 Référence CVE CVE-2022-34760 https://www.cve.org/CVERecord?id=CVE-2022-34760 Référence CVE CVE-2022-34761 https://www.cve.org/CVERecord?id=CVE-2022-34761 Référence CVE CVE-2022-34762 https://www.cve.org/CVERecord?id=CVE-2022-34762 Référence CVE CVE-2022-34763 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-628Multiples vulnérabilités dans les produits Schneider Electric

d?id=CVE-2021-21811 Référence CVE CVE-2021-21812 https://www.cve.org/CVERecord?id=CVE-2021-21812 Référence CVE CVE-2021-21813 https://www.cve.org/CVERecord?id=CVE-2021-21813 Référence CVE CVE-2021-21814 https://www.cve.org/CVERecord?id=CVE-2021-21814 Référence CVE CVE-2021-21815 https://www.cve.org/CVERecord?id=CVE-2021-21815 Référence CVE CVE-2021-21825 https://www.cve.org/CVERecord?id=CVE-2021-21825 Référence CVE CVE-2021-21826 https://www.cve.org/CVERecord?id=CVE-2021-21826 Référence CVE CVE-2021-21827 https://www.cve.org/CVERecord?id=CVE-2021-21827 Référence CVE CVE-2021-21828 https://www.cve.org/CVERecord?id=CVE-2021-21828 Référence CVE CVE-2021-21829 https://www.cve.org/CVERecord?id=CVE-2021-21829 Référence CVE CVE-2021-21830 https://www.cve.org/CVERecord?id=CVE-2021-21830 Référence CVE CVE-2021-21863 https://www.cve.org/CVERecord?id=CVE-2021-21863 Référence CVE CVE-2021-21864 https://www.cve.org/CVERecord?id=CVE-2021-21864 Référence CVE CVE-2021-21865 https://www.cve.org/CVERecord?id=CVE-2021-21865 Référence CVE CVE-2021-21866 https://www.cve.org/CVERecord?id=CVE-2021-21866 Référence CVE CVE-2021-21867 https://www.cve.org/CVERecord?id=CVE-2021-21867 Référence CVE CVE-2021-21868 https://www.cve.org/CVERecord?id=CVE-2021-21868 Référence CVE CVE-2021-21869 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2022-AVI-215Multiples vulnérabilités dans les produits Schneider

d?id=CVE-2021-21811 Référence CVE CVE-2021-21812 https://www.cve.org/CVERecord?id=CVE-2021-21812 Référence CVE CVE-2021-21813 https://www.cve.org/CVERecord?id=CVE-2021-21813 Référence CVE CVE-2021-21814 https://www.cve.org/CVERecord?id=CVE-2021-21814 Référence CVE CVE-2021-21815 https://www.cve.org/CVERecord?id=CVE-2021-21815 Référence CVE CVE-2021-21825 https://www.cve.org/CVERecord?id=CVE-2021-21825 Référence CVE CVE-2021-21826 https://www.cve.org/CVERecord?id=CVE-2021-21826 Référence CVE CVE-2021-21827 https://www.cve.org/CVERecord?id=CVE-2021-21827 Référence CVE CVE-2021-21828 https://www.cve.org/CVERecord?id=CVE-2021-21828 Référence CVE CVE-2021-21829 https://www.cve.org/CVERecord?id=CVE-2021-21829 Référence CVE CVE-2021-21830 https://www.cve.org/CVERecord?id=CVE-2021-21830 Référence CVE CVE-2021-22778 https://www.cve.org/CVERecord?id=CVE-2021-22778 Référence CVE CVE-2021-22779 https://www.cve.org/CVERecord?id=CVE-2021-22779 Référence CVE CVE-2021-22780 https://www.cve.org/CVERecord?id=CVE-2021-22780 Référence CVE CVE-2021-22781 https://www.cve.org/CVERecord?id=CVE-2021-22781 Référence CVE CVE-2021-22782 https://www.cve.org/CVERecord?id=CVE-2021-22782 Référence CVE CVE-2021-22783 https://www.cve.org/CVERecord?id=CVE-2021-22783 Référence CVE CVE-2021-22797 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-622Multiples vulnérabilités dans les produits Schneider Electric

d?id=CVE-2021-21811 Référence CVE CVE-2021-21812 https://www.cve.org/CVERecord?id=CVE-2021-21812 Référence CVE CVE-2021-21813 https://www.cve.org/CVERecord?id=CVE-2021-21813 Référence CVE CVE-2021-21814 https://www.cve.org/CVERecord?id=CVE-2021-21814 Référence CVE CVE-2021-21815 https://www.cve.org/CVERecord?id=CVE-2021-21815 Référence CVE CVE-2021-21825 https://www.cve.org/CVERecord?id=CVE-2021-21825 Référence CVE CVE-2021-21826 https://www.cve.org/CVERecord?id=CVE-2021-21826 Référence CVE CVE-2021-21827 https://www.cve.org/CVERecord?id=CVE-2021-21827 Référence CVE CVE-2021-21828 https://www.cve.org/CVERecord?id=CVE-2021-21828 Référence CVE CVE-2021-21829 https://www.cve.org/CVERecord?id=CVE-2021-21829 Référence CVE CVE-2021-21830 https://www.cve.org/CVERecord?id=CVE-2021-21830 Référence CVE CVE-2021-22704 https://www.cve.org/CVERecord?id=CVE-2021-22704 Référence CVE CVE-2021-22775 https://www.cve.org/CVERecord?id=CVE-2021-22775 Référence CVE CVE-2021-22789 https://www.cve.org/CVERecord?id=CVE-2021-22789 Référence CVE CVE-2021-22790 https://www.cve.org/CVERecord?id=CVE-2021-22790 Référence CVE CVE-2021-22791 https://www.cve.org/CVERecord?id=CVE-2021-22791 Référence CVE CVE-2021-22792 https://www.cve.org/CVERecord?id=CVE-2021-22792 Référence CVE CVE-2021-22793 https://www.cve.org/CVERecord?id=

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
Action
V15.1 HF001 of EcoStruxure™ Control Expert includes a fix for these vulnerabilities and is available for download here: https://www.se.com/ww/en/download/document/ControlExpert_V151_HF001/ If customers choose not to apply the remediation provided above, they should immediately apply the following mitigations to reduce the risk of exploit: • Store the project files in a secure storage and restrict the access to only trusted users • When exchanging files over the network, use secure communication channels • Only open project files received from a trusted source • Compute a hash of the project files and regularly check the consistency of this hash to verify the integrity before usage • Harden the workstation running EcoStruxure Control Expert or Unity Pro • Customers using Unity Pro should strongly consider migrating to EcoStruxure Control Expert.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 13 Aug 2021 · Last source change 3 Aug 2024, 18:23 UTC · CWE-122 · Heap-based Buffer Overflow

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-9000
Product sourceVendor CSAF · Schneider Electric CPCERT
Remediation sourceVendor CSAF · Schneider Electric CPCERT
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2021-9000↗Vendor CSAF · Schneider Electric CPCERT↗Public exploit reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-21829 · cve.blacktree.nl