CVE-2012-3946: n/a vulnerability

CVE-2012-3946: Cisco IOS before 15.3(2)S allows remote attackers to bypass interface ACL restrictions in opportunistic cir...

Cisco IOS before 15.3(2)S allows remote attackers to bypass interface ACL restrictions in opportunistic circumstances by sending IPv6 packets in an unspecified scenario in which expected packet drops do not occur for "a small percentage" of the packets, aka Bug ID CSCty73682.

UnknownCVSS not scoredNot KEV-listedUpdatedAug 6, 2024, 20:21 UTC (UTC+00:00)

Security readout for executives and security teams

This flaw could let some IPv6 traffic pass through Cisco IOS interface ACLs that should have blocked it. The source describes the bypass as occurring only for a small percentage of packets in unspecified circumstances, so impact is real but not well quantified. Exposure is most relevant to organizations running Cisco IOS versions before 15.3(2)S with IPv6 enabled and interface ACLs relied on for traffic filtering. The structured affected-product data is incomplete. Treat this as a targeted network-infrastructure review item, not an emergency based on current evidence. Prioritize remediation where older Cisco IOS routers enforce IPv6 perimeter or segmentation controls. Mitigation focus: Inventory Cisco IOS devices and record exact software versions.; Prioritize devices using IPv6 interface ACLs for review.; Consult Cisco guidance for CSCty73682 and affected trains..

Prepared: Jun 14, 2026, 14:32 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: Apr 24, 2014, 10:00 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

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Weakness

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