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Vulnerabilities

Vulnerability · CVE-2026-76505

Cisco IOS XR Software for ASR 9000 Series Routers IPv4 Unicast Packets Denial of Service Vulnerability

Published Oct 21, 2026 · catalog updated Oct 22, 2026 · Cisco Cisco IOS XR Software

Last checked Oct 25, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-76505. EPSS is 0.34%. Act only if a listed version of Cisco Cisco IOS XR Software is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.34%
Remediation
Advisory link
Affected products
vendor Cisco Cisco IOS XR Software

A vulnerability in the IPv4 packet processing functionality of Cisco IOS XR Software that affects Cisco ASR 9000 and 9900 Series Aggregation Services Routers as well as Cisco ASR 9902 and 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause network processor (NP) errors, resulting in a line card reset or shutdown and a denial of service (DoS) condition. This vulnerability is due to the incorrect handling of crafted IPv4 packets that are received on an affected line card interface and processed as for-us traffic. The issue can result in an NP reset, causing traffic loss on the affected line card while it recovers. Under repeated reset conditions, the network processor may enter a persistent shutdown state, in which case an explicit line card reload may be required to restore traffic. The vulnerability is within the IPv4 packet-processing path. Transit IPv4 traffic does not trigger this issue and IPv6 traffic cannot trigger it.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Cisco Cisco IOS XR Softwareversion unspecified

How to fix CVE-2026-76505

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-76505. EPSS is 0.34%. Act only if a listed version of Cisco Cisco IOS XR Software is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-20: Improper Input Validation. EPSS 0.34%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Cisco security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 21, 2026 · NIST NVD

    Detected

    A vulnerability in the IPv4 packet processing functionality of Cisco IOS XR Software that affects Cisco ASR 9000 and 9900 Series Aggregation Services Routers as well as Cisco ASR 9902 and 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause network processor (NP) errors, resulting in a line card reset or shutdown and a denial of service (DoS) condition. Th

  2. Oct 22, 2026 · NIST NVD

    Updated

    A vulnerability in the IPv4 packet processing functionality of Cisco IOS XR Software that affects Cisco ASR 9000 and 9900 Series Aggregation Services Routers as well as Cisco ASR 9902 and 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause network processor (NP) errors, resulting in a line card reset or shutdown and a denial of service (DoS) condition. Th

Sources

  • Cisco Security AdvisoriesVendor advisoryCVE-2026-76505

    A vulnerability in the IPv4 packet processing functionality of Cisco IOS XR Software that affects Cisco ASR 9000 and 9900 Series Aggregation Services Routers as well as Cisco ASR 9902 and 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cau

    sec.cloudapps.cisco.com
  • CVE.orgVulnerability recordCVE-2026-76505

    A vulnerability in the IPv4 packet processing functionality of Cisco IOS XR Software that affects Cisco ASR 9000 and 9900 Series Aggregation Services Routers as well as Cisco ASR 9902 and 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cau

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-76505

    30-day exploitation probability 0.34%

    first.org
  • NIST NVDVulnerability recordCVE-2026-76505

    A vulnerability in the IPv4 packet processing functionality of Cisco IOS XR Software that affects Cisco ASR 9000 and 9900 Series Aggregation Services Routers as well as Cisco ASR 9902 and 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cau

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Cisco Security AdvisoriesOct 25, 2026
  • FIRST EPSSOct 23, 2026
  • NIST NVDOct 22, 2026
  • CVE.orgOct 21, 2026