CVE-2005-4440: n/a vulnerability

CVE-2005-4440: The 802.1q VLAN protocol allows remote attackers to bypass network segmentation and spoof VLAN traffic via...

The 802.1q VLAN protocol allows remote attackers to bypass network segmentation and spoof VLAN traffic via a message with two 802.1q tags, which causes the second tag to be redirected from a downstream switch after the first tag has been stripped, as demonstrated by Yersinia, aka "double-tagging VLAN jumping attack."

UnknownCVSS not scoredNot KEV-listedUpdatedAug 7, 2024, 23:46 UTC (UTC+00:00)

Security readout for executives and security teams

This CVE describes a VLAN segmentation bypass, not a named product bug. Under certain switch configurations, specially tagged network traffic may cross VLAN boundaries, weakening isolation between user, server, or management networks. Exposure depends on switch topology and VLAN configuration. Networks relying on VLANs as a security boundary, especially where untrusted devices share switching infrastructure with sensitive VLANs, should review risk. Treat this as a network design and configuration assurance issue. It is not currently sourced as exploited, but it matters where VLANs protect critical systems from less trusted networks. Mitigation focus: Check current switch vendor guidance for double-tagging VLAN-jumping protections.; Review trunk, access-port, and native-VLAN configurations against vendor hardening guidance.; Do not treat VLAN segmentation alone as proof of strong security isolation..

Prepared: Jun 29, 2026, 15:49 UTC (UTC+00:00)

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

Potential ATT&CK relevance

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Vulnerability profileCVE Program record

Severity: Unknown
CVSS: Not scored
Known Exploited: No
Published: Dec 21, 2005, 02:00 UTC (UTC+00:00)

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

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0CVSS vectors

0Timeline events

0ADP providers

1Source links

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Source materials

CVE List V5 sourceCVE List V5

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus

n/an/an/aListed

Weakness

CWE details

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