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TI-2021-00947 Aliases CVE-2021-1220GHSA-4m9r-j9f4-4m4g

Cisco IOS XE Software Web UI Denial of Service Vulnerabilities

Priority LOW 22CWE-20Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
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

Multiple vulnerabilities in the web UI of Cisco IOS XE Software could allow an authenticated, remote attacker with read-only privileges to cause the web UI software to become unresponsive and consume vty line instances, resulting in a denial of service (DoS) condition. These vulnerabilities are due to insufficient error handling in the web UI. An attacker could exploit these vulnerabilities by sending crafted HTTP packets to an affected device. A successful exploit could allow the attacker to cause the web UI software to become unresponsive and consume all available vty lines, preventing new session establishment and resulting in a DoS condition. Manual intervention would be required to regain web UI and vty session functionality. Note: These vulnerabilities do not affect the console connection.

Why it matters now

EPSS 0.00977 62nd percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

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 · 35

CPEVersionsRoleVendor
cpe:2.3:o:cisco:ios_xe:3.15.1xbs:*:*:*:*:*:*:*3.15.1xbsVulnerableCisco
cpe:2.3:o:cisco:ios_xe:3.15.2xbs:*:*:*:*:*:*:*3.15.2xbsVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.11.1:*:*:*:*:*:*:*16.11.1VulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.11.1a:*:*:*:*:*:*:*16.11.1aVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.11.1b:*:*:*:*:*:*:*16.11.1bVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.11.1c:*:*:*:*:*:*:*16.11.1cVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.11.1s:*:*:*:*:*:*:*16.11.1sVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.11.2:*:*:*:*:*:*:*16.11.2VulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.1:*:*:*:*:*:*:*16.12.1VulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.1a:*:*:*:*:*:*:*16.12.1aVulnerableCisco
  • cpe:2.3:o:cisco:ios_xe:3.15.1xbs:*:*:*:*:*:*:* Versions 3.15.1xbs Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:3.15.2xbs:*:*:*:*:*:*:* Versions 3.15.2xbs Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.11.1:*:*:*:*:*:*:* Versions 16.11.1 Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.11.1a:*:*:*:*:*:*:* Versions 16.11.1a Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.11.1b:*:*:*:*:*:*:* Versions 16.11.1b Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.11.1c:*:*:*:*:*:*:* Versions 16.11.1c Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.11.1s:*:*:*:*:*:*:* Versions 16.11.1s Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.11.2:*:*:*:*:*:*:* Versions 16.11.2 Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.1:*:*:*:*:*:*:* Versions 16.12.1 Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.1a:*:*:*:*:*:*:* Versions 16.12.1a Vulnerable ·Cisco
Show 25 more CPE
CPEVersionsRoleVendor
cpe:2.3:o:cisco:ios_xe:16.12.1c:*:*:*:*:*:*:*16.12.1cVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.1s:*:*:*:*:*:*:*16.12.1sVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.1t:*:*:*:*:*:*:*16.12.1tVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.1w:*:*:*:*:*:*:*16.12.1wVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.1x:*:*:*:*:*:*:*16.12.1xVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.1y:*:*:*:*:*:*:*16.12.1yVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.1z:*:*:*:*:*:*:*16.12.1zVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.2:*:*:*:*:*:*:*16.12.2VulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.2a:*:*:*:*:*:*:*16.12.2aVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.2s:*:*:*:*:*:*:*16.12.2sVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.2t:*:*:*:*:*:*:*16.12.2tVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.3:*:*:*:*:*:*:*16.12.3VulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.3a:*:*:*:*:*:*:*16.12.3aVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.3s:*:*:*:*:*:*:*16.12.3sVulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.4:*:*:*:*:*:*:*16.12.4VulnerableCisco
cpe:2.3:o:cisco:ios_xe:16.12.4a:*:*:*:*:*:*:*16.12.4aVulnerableCisco
cpe:2.3:o:cisco:ios_xe:17.1.1:*:*:*:*:*:*:*17.1.1VulnerableCisco
cpe:2.3:o:cisco:ios_xe:17.1.1a:*:*:*:*:*:*:*17.1.1aVulnerableCisco
cpe:2.3:o:cisco:ios_xe:17.1.1s:*:*:*:*:*:*:*17.1.1sVulnerableCisco
cpe:2.3:o:cisco:ios_xe:17.1.1t:*:*:*:*:*:*:*17.1.1tVulnerableCisco
cpe:2.3:o:cisco:ios_xe:17.1.2:*:*:*:*:*:*:*17.1.2VulnerableCisco
cpe:2.3:o:cisco:ios_xe:17.2.1:*:*:*:*:*:*:*17.2.1VulnerableCisco
cpe:2.3:o:cisco:ios_xe:17.2.1a:*:*:*:*:*:*:*17.2.1aVulnerableCisco
cpe:2.3:o:cisco:ios_xe:17.2.1r:*:*:*:*:*:*:*17.2.1rVulnerableCisco
cpe:2.3:o:cisco:ios_xe:17.2.1v:*:*:*:*:*:*:*17.2.1vVulnerableCisco
  • cpe:2.3:o:cisco:ios_xe:16.12.1c:*:*:*:*:*:*:* Versions 16.12.1c Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.1s:*:*:*:*:*:*:* Versions 16.12.1s Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.1t:*:*:*:*:*:*:* Versions 16.12.1t Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.1w:*:*:*:*:*:*:* Versions 16.12.1w Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.1x:*:*:*:*:*:*:* Versions 16.12.1x Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.1y:*:*:*:*:*:*:* Versions 16.12.1y Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.1z:*:*:*:*:*:*:* Versions 16.12.1z Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.2:*:*:*:*:*:*:* Versions 16.12.2 Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.2a:*:*:*:*:*:*:* Versions 16.12.2a Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.2s:*:*:*:*:*:*:* Versions 16.12.2s Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.2t:*:*:*:*:*:*:* Versions 16.12.2t Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.3:*:*:*:*:*:*:* Versions 16.12.3 Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.3a:*:*:*:*:*:*:* Versions 16.12.3a Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.3s:*:*:*:*:*:*:* Versions 16.12.3s Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.4:*:*:*:*:*:*:* Versions 16.12.4 Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:16.12.4a:*:*:*:*:*:*:* Versions 16.12.4a Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:17.1.1:*:*:*:*:*:*:* Versions 17.1.1 Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:17.1.1a:*:*:*:*:*:*:* Versions 17.1.1a Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:17.1.1s:*:*:*:*:*:*:* Versions 17.1.1s Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:17.1.1t:*:*:*:*:*:*:* Versions 17.1.1t Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:17.1.2:*:*:*:*:*:*:* Versions 17.1.2 Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:17.2.1:*:*:*:*:*:*:* Versions 17.2.1 Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:17.2.1a:*:*:*:*:*:*:* Versions 17.2.1a Vulnerable ·Cisco
  • cpe:2.3:o:cisco:ios_xe:17.2.1r:*:*:*:*:*:*:* Versions 17.2.1r 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.

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Advisory ·

    Cisco IOS XE Software — 20210324 Cisco IOS XE Software Web UI Denial of Service Vulnerabilities

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2021-01083 Cisco IOS XE Software Web UI Denial of Service VulnerabilitiesPriority LOW 22
    Show all 2 records → Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-1220
  2. 2026-10-03 Alias added: GHSA-4m9r-j9f4-4m4g

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