Read the docs
TI-2021-01121 Aliases CVE-2021-1394GHSA-x482-c63f-45hq

Cisco IOS XE Software for Network Convergence System 520 Routers Denial of Service Vulnerability

Priority LOW 33CWE-399Published · Updated

Key facts

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

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

Summary

A vulnerability in the ingress traffic manager of Cisco IOS XE Software for Cisco Network Convergence System (NCS) 520 Routers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the web management interface of an affected device. This vulnerability is due to incorrect processing of certain IPv4 TCP traffic that is destined to an affected device. An attacker could exploit this vulnerability by sending a large number of crafted TCP packets to the affected device. A successful exploit could allow the attacker to cause the web management interface to become unavailable, resulting in a DoS condition. Note: This vulnerability does not impact traffic that is going through the device or going to the Management Ethernet interface of the device.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01319 71st 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
Yes
Technical impact
Partial

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

Affected products

VendorProductAffected versionsFixed inStatusSource
CiscoCisco IOS XE Softwareall versions—No fix listedCNA
  • Cisco IOS XE Software VendorCisco Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 10

CPEVersionsRoleVendor
cpe:2.3:o:cisco:ios_xe:16.10.1:*:*:*:*:*:*:*16.10.1VulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.10.1a:*:*:*:*:*:*:*16.10.1aVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.10.1b:*:*:*:*:*:*:*16.10.1bVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.10.1c:*:*:*:*:*:*:*16.10.1cVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.10.1d:*:*:*:*:*:*:*16.10.1dVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.10.1e:*:*:*:*:*:*:*16.10.1eVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.10.1f:*:*:*:*:*:*:*16.10.1fVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.10.1g:*:*:*:*:*:*:*16.10.1gVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.10.1s:*:*:*:*:*:*:*16.10.1sVulnerableCisco
cpe:2.3:o:cisco:ios_xe:17.2.1v:*:*:*:*:*:*:*17.2.1vVulnerableCisco
  • cpe:2.3:o:cisco:ios_xe:16.10.1:*:*:*:*:*:*:* Versions 16.10.1 Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.10.1a:*:*:*:*:*:*:* Versions 16.10.1a Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.10.1b:*:*:*:*:*:*:* Versions 16.10.1b Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.10.1c:*:*:*:*:*:*:* Versions 16.10.1c Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.10.1d:*:*:*:*:*:*:* Versions 16.10.1d Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.10.1e:*:*:*:*:*:*:* Versions 16.10.1e Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.10.1f:*:*:*:*:*:*:* Versions 16.10.1f Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.10.1g:*:*:*:*:*:*:* Versions 16.10.1g Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.10.1s:*:*:*:*:*:*:* Versions 16.10.1s Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:17.2.1v:*:*:*:*:*:*:* Versions 17.2.1v Vulnerable ·Cisco

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-1394
  2. 2026-10-03 Alias added: GHSA-x482-c63f-45hq

References

Advisory 1

  • TI-2023-06904 Cisco is providing an update for the ongoing investigation into observed exploitation of… KEVCVSS 3.1CRITICAL 10.0
  • TI-2018-00122 Memory corruption in Cisco IOS and IOS XE KEVCVSS 3.1CRITICAL 9.8
  • TI-2017-02977 Improper input validation in Cisco IOS and IOS XE Software KEVCVSS 3.1CRITICAL 9.8
  • TI-2018-00135 Memory corruption in Cisco IOS, IOS XE, and IOS XR KEVCVSS 3.1HIGH 8.8
  • TI-2017-04498 Memory corruption in Cisco IOS KEVCVSS 3.1HIGH 8.8
  • TI-2017-04497 Memory corruption in Cisco IOS XE Software KEVCVSS 3.1HIGH 8.8
See all 561 →

Sources

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