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TI-2021-01347 Aliases CVE-2021-1625GHSA-w3v7-hj7c-4j8f

Cisco IOS XE Software Zone-Based Policy Firewall ICMP and UDP Inspection Vulnerability

Priority LOW 34CWE-284Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-284.

Summary

A vulnerability in the Zone-Based Policy Firewall feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to prevent the Zone-Based Policy Firewall from correctly classifying traffic. This vulnerability exists because ICMP and UDP responder-to-initiator flows are not inspected when the Zone-Based Policy Firewall has either Unified Threat Defense (UTD) or Application Quality of Experience (AppQoE) configured. An attacker could exploit this vulnerability by attempting to send UDP or ICMP flows through the network. A successful exploit could allow the attacker to inject traffic through the Zone-Based Policy Firewall, resulting in traffic being dropped because it is incorrectly classified or in incorrect reporting figures being produced by high-speed logging (HSL).

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00909 60th 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 · 1

CPEVersionsRoleVendor
cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:*before 17.3.2VulnerableCisco
  • cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:* Versions before 17.3.2 Vulnerable ·Cisco

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-1625
  2. 2026-10-03 Alias added: GHSA-w3v7-hj7c-4j8f

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