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CVE Record

CVE-2021-33577: An issue was discovered in Cleo LexiCom 5.5.0.0.

An issue was discovered in Cleo LexiCom 5.5.0.0. The requirement for the sender of an AS2 message to identify themselves (via encryption and signing of the message) can be bypassed by changing the Content-Type of the message to text/plain.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-33577 affects Cleo LexiCom 5.5.0.0 and can undermine AS2 sender identity checks. In business terms, a trading-partner file transfer workflow may accept a message without the expected signing and encryption proof. Public sources do not provide a CVSS score, confirmed impact scope, patch version, or active exploitation evidence.

Executive priority

Treat this as a targeted managed file transfer risk, not a confirmed emergency. Prioritize inventory and vendor verification if LexiCom 5.5.0.0 supports business-critical partner transfers, especially where AS2 endpoints are externally reachable.

Technical view

The CVE describes an AS2 message handling weakness in Cleo LexiCom 5.5.0.0 where the requirement for sender identification through encryption and signing can be bypassed through Content-Type handling. The available record does not name a CWE, CVSS vector, fixed release, or affected versions beyond 5.5.0.0.

Likely exposure

Exposure is most likely where Cleo LexiCom 5.5.0.0 processes AS2 messages from external or partner networks. Systems not using AS2, not running LexiCom, or not on the named version are not shown as affected by the provided sources.

Exploitation context

The CVE is not listed in KEV, and the provided bundle does not cite active exploitation. The public description gives a bypass condition, but does not provide evidence of in-the-wild use, exploit tooling, or broad version impact.

Researcher notes

Evidence is limited to the CVE description and referenced advisory/product pages. The core issue is authentication enforcement bypass in AS2 Content-Type handling. No CVSS, CWE, patch version, exploit status, or broader affected-version range is available in the provided bundle.

Mitigation direction

  • Identify any Cleo LexiCom 5.5.0.0 deployments handling AS2 traffic.
  • Check Cleo guidance for fixed versions or vendor-supported remediation.
  • Restrict AS2 endpoints to trusted partner networks where feasible.
  • Review partner authentication requirements for signing and encryption enforcement.
  • Increase monitoring for malformed or unexpected AS2 message metadata.

Validation and detection

  • Confirm the installed Cleo LexiCom version on all managed file transfer hosts.
  • Inventory AS2 endpoints exposed to internet, partner VPNs, or shared networks.
  • Review AS2 logs for messages lacking expected signing or encryption evidence.
  • Verify partner profiles require sender identification controls.
  • Document whether vendor guidance or upgrade evidence exists.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2021-33577 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.