Cyber Resilience

CVE-2021-34703

Medium

Published: 23 September 2021

Published
23 September 2021
Modified
21 November 2024
KEV Added
Patch
CVSS Score v3.1 6.8 CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
EPSS Score 0.0024 47.9th percentile
Risk Priority 14 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-34703 is a medium-severity Missing Initialization of a Variable (CWE-456) vulnerability in Cisco Ios. Its CVSS base score is 6.8 (Medium).

Operationally, ranked at the 47.9th 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 the Link Layer Discovery Protocol (LLDP) message parser of Cisco IOS Software and Cisco IOS XE Software could allow an attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition.…

more

This vulnerability is due to improper initialization of a buffer. An attacker could exploit this vulnerability via any of the following methods: An authenticated, remote attacker could access the LLDP neighbor table via either the CLI or SNMP while the device is in a specific state. An unauthenticated, adjacent attacker could corrupt the LLDP neighbor table by injecting specific LLDP frames into the network and then waiting for an administrator of the device or a network management system (NMS) managing the device to retrieve the LLDP neighbor table of the device via either the CLI or SNMP. An authenticated, adjacent attacker with SNMP read-only credentials or low privileges on the device CLI could corrupt the LLDP neighbor table by injecting specific LLDP frames into the network and then accessing the LLDP neighbor table via either the CLI or SNMP. A successful exploit could allow the attacker to cause the affected device to crash, resulting in a reload of the device.

CWE(s)

Related Threats

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

Affected Assets

cisco
ios
≤ 16.12.3
cisco
ios xe
≤ 16.12.3

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-665

Ensures shared resources are explicitly initialized or cleared on allocation, preventing exposure of prior contents to new users or processes.

addresses: CWE-665

Mandates that every instance begins in a known (presumably clean) state, eliminating reliance on residual or uninitialized state left by prior executions.

References