HOMEVULNERABILITIESCVE-2021-33576
CRITICAL

CVE-2021-33576

CWE-22Published: June 18, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

An issue was discovered in Cleo LexiCom 5.5.0.0. Within the AS2 message, the sender can specify a filename. This filename can include path-traversal characters, allowing the file to be written to an arbitrary location on disk.

NVD Source

Technical Analysis

CVE-2021-33576 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

cleo1 product(s)
lexicom
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://github.com/atredispartners/advisories/blob/master/ATREDIS-2020-0011.md
ADVISORYhttps://github.com/atredispartners/advisories/blob/master/ATREDIS-2020-0011.md

All References (4)

→
https://github.com/atredispartners/advisories/blob/master/ATREDIS-2020-0011.mdExploit · Third Party Advisory
→
https://www.cleo.com/cleo-lexicomProduct
→
https://github.com/atredispartners/advisories/blob/master/ATREDIS-2020-0011.mdExploit · Third Party Advisory
→
https://www.cleo.com/cleo-lexicomProduct

Quick Facts

CVE IDCVE-2021-33576
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-22
CISA KEVNo
Affected1 vendor(s)
PublishedJun 18, 2021

Related CVEs (CWE-22)

CVE-2015-0779
10.0
CVE-2014-3914
10.0
CVE-2026-59555
10.0
CVE-2013-6221
10.0
CVE-2010-5323
10.0
CVE-2008-6833
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-33576 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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