TI-2021-00995 Aliases CVE-2021-1268 GHSA-374q-g769-jjp8

Cisco IOS XR Software IPv6 Flood Denial of Service Vulnerability

LOW 33CWE-1076Published 2021-02-04 · Updated 2024-11-08

Key facts

Attack vector: Adjacent network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: None · None · High
Fix status: No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

A vulnerability in the IPv6 protocol handling of the management interfaces of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause an IPv6 flood on the management interface network of an affected device. The vulnerability exists because the software incorrectly forwards IPv6 packets that have an IPv6 node-local multicast group address destination and are received on the management interfaces. An attacker could exploit this vulnerability by connecting to the same network as the management interfaces and injecting IPv6 packets that have an IPv6 node-local multicast group address destination. A successful exploit could allow the attacker to cause an IPv6 flood on the corresponding network. Depending on the number of Cisco IOS XR Software nodes on that network segment, exploitation could cause excessive network traffic, resulting in network degradation or a denial of service (DoS) condition.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00509 43rd percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Cisco	Cisco IOS XR Software	all versions	—	No fix listed	CNA

Cisco IOS XR Software VendorCisco Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 4

CPE	Versions	Role	Vendor
cpe:2.3:o:cisco:ios_xr::::::::	before 6.7.3; 7.1.0 to before 7.1.3; 7.2.0 to before 7.2.2	Vulnerable	Cisco
cpe:2.3:o:cisco:ios_xr:7.3.0:::::::*	7.3.0	Vulnerable	Cisco
cpe:2.3:h:cisco:ncs_1001:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:ncs_1002:-:::::::*	not specified by NVD	Running on	Cisco

cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* Versions before 6.7.3; 7.1.0 to before 7.1.3; 7.2.0 to before 7.2.2 Vulnerable ·Cisco
cpe:2.3:o:cisco:ios_xr:7.3.0:*:*:*:*:*:*:* Versions 7.3.0 Vulnerable ·Cisco
cpe:2.3:h:cisco:ncs_1001:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:ncs_1002:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2021-1268
2026-10-03 Alias added: GHSA-374q-g769-jjp8

References

Advisory 1

20210203 Cisco IOS XR Software IPv6 Flood Denial of Service Vulnerability

TI-2020-02680 Cisco IOS XR Software Cisco Discovery Protocol Format String Vulnerability KEVCVSS 3.1HIGH 8.8
TI-2018-00135 Memory corruption in Cisco IOS, IOS XE, and IOS XR KEVCVSS 3.1HIGH 8.8
TI-2020-03113 Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerabilities KEVCVSS 3.1HIGH 8.6
TI-2020-03110 Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerability KEVCVSS 3.1HIGH 8.6
TI-2018-00142 Memory corruption in Cisco IOS, IOS XE, and IOS XR KEVCVSS 3.1HIGH 8.0
TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5

See all 199 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences