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CVE Record

CVE-2006-3216: Clearswift MAILsweeper for SMTP before 4.3.20 and MAILsweeper for Exchange before 4.3.20 allows remote atta...

Clearswift MAILsweeper for SMTP before 4.3.20 and MAILsweeper for Exchange before 4.3.20 allows remote attackers to cause a denial of service via (1) non-ASCII characters in a reverse DNS lookup result from a Received header, which leads to a Receiver service stop, and (2) unspecified vectors involving malformed messages, which causes "unpredictable behavior" that prevents the Security service from processing more messages.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's Takemoderate

Analyst readout for executives and security teams

Plain-English summary

This is a legacy denial-of-service issue in Clearswift MAILsweeper mail filtering products before version 4.3.20. A crafted or malformed email-related condition could stop mail receiver or security processing services, disrupting email flow or inspection. It is mainly urgent for organizations still running these old products.

Executive priority

Prioritize as a legacy availability risk. It is not presented as data theft or code execution, but an affected mail gateway could disrupt business email and weaken message inspection. Address promptly if these products still exist in production.

Technical view

MAILsweeper for SMTP and Exchange before 4.3.20 can fail when processing non-ASCII reverse DNS data from a Received header or unspecified malformed messages. Reported impacts include Receiver service stoppage and Security service behavior that prevents further message processing. CVSS, CWE, and detailed exploit mechanics are not provided.

Likely exposure

Exposure is limited to environments still running Clearswift MAILsweeper for SMTP or Exchange before 4.3.20, especially systems processing inbound email. Modern environments are unlikely to be affected unless this legacy gateway remains in production or in an internal mail path.

Exploitation context

The CVE states remote attackers can cause denial of service. The source bundle does not show CISA KEV listing, active exploitation, public exploit confirmation, or detailed weaponization evidence. Treat exploitation status as unconfirmed.

Researcher notes

The record lacks CVSS, CWE, and detailed affected CPE data. The affected products and version boundary come from the CVE description. Avoid assuming specific malformed-message formats, exploit availability, or fixes beyond the stated 4.3.20 version boundary and vendor guidance.

Mitigation direction

  • Inventory MAILsweeper SMTP and Exchange deployments and confirm exact versions.
  • Upgrade affected installations to 4.3.20 or later per vendor guidance.
  • Retire unsupported legacy MAILsweeper systems where upgrade is not practical.
  • Monitor mail gateway services for unexpected Receiver or Security service stops.
  • Review vendor documentation before applying compensating controls.

Validation and detection

  • Check whether MAILsweeper for SMTP or Exchange is installed anywhere in mail flow.
  • Verify deployed versions are not earlier than 4.3.20.
  • Review mail gateway logs for service stops during message processing.
  • Confirm inbound mail still passes through supported filtering infrastructure.
  • Document any legacy exceptions and compensating monitoring.
Prepared
Confidence
medium
Sources
8

Public sources used

Based on public source material and reviewed before publication.

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-2006-3216 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
9Source 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.