#VU56859 Always-Incorrect Control Flow Implementation in Cisco Systems, Inc products - CVE-2021-34767

Vulnerability identifier: #VU56859

Vulnerability risk: Medium

CVSSv4.0: 4.9 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-34767

CWE-ID: CWE-670

Exploitation vector: Local network

Exploit availability: No

Vulnerable software:
Cisco IOS XE
Operating systems & Components / Operating system
Cisco Catalyst 9800 Wireless Controller
Hardware solutions / Routers & switches, VoIP, GSM, etc
Catalyst 9800 Wireless Controllers for Cloud
Other software / Other software solutions

Vendor: Cisco Systems, Inc

Description

The vulnerability allows a remote attacker to perform a denial of servide (DoS) attack.

The vulnerability exists due to a logic error when processing specific link-local IPv6 traffic. A remote attacker on the local network can send a specially crafted IPv6 packet and cause a denial of service condition on the target system.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Cisco IOS XE: All versions

Cisco Catalyst 9800 Wireless Controller: All versions

Catalyst 9800 Wireless Controllers for Cloud: All versions

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External links
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ewlc-ipv6-dos-NMYeCnZv

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.