Cyber Resilience

CVE-2021-34767

High

Published: 23 September 2021

Published
23 September 2021
Modified
30 October 2025
KEV Added
Patch
CVSS Score v3.1 7.4 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS Score 0.0010 27.3th percentile
Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-34767 is a high-severity Always-Incorrect Control Flow Implementation (CWE-670) vulnerability in Cisco Ios Xe. Its CVSS base score is 7.4 (High).

Operationally, ranked at the 27.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

A vulnerability in IPv6 traffic processing of Cisco IOS XE Wireless Controller Software for Cisco Catalyst 9000 Family Wireless Controllers could allow an unauthenticated, adjacent attacker to cause a Layer 2 (L2) loop in a configured VLAN, resulting in a…

more

denial of service (DoS) condition for that VLAN. The vulnerability is due to a logic error when processing specific link-local IPv6 traffic. An attacker could exploit this vulnerability by sending a crafted IPv6 packet that would flow inbound through the wired interface of an affected device. A successful exploit could allow the attacker to cause traffic drops in the affected VLAN, thus triggering the DoS condition.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

cisco
ios xe
16.10.1, 16.10.1a, 16.10.1b, 16.10.1c, 16.10.1d

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References