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CVE-2026-76505— Cisco IOS XR Software for ASR 9000 Series Routers IPv4 Unicast Packets Denial of Service Vulnerability

Quick assessment

Affected
Cisco Cisco IOS XR Software
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

思科 IOS XR 软件中的 IPv4 数据包处理功能存在一项漏洞，该漏洞影响思科 ASR 9000 和 9900 系列聚合服务路由器，以及思科 ASR 9902 和 9903 紧凑型高性能路由器。此漏洞可能使未经身份验证的远程攻击者引发网络处理器（NP）错误，从而导致线卡重置或关闭，并造成拒绝服务（DoS）状况。 该漏洞源于对接收于受影响线卡接口、并被处理为“发往本机”（for-us）流量的精心构造 IPv4 数据包的处理不当。此问题可能导致网络处理器重置，进而使受影响线卡在恢复期间出现流量丢失。若反复触发重置，

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 53

VendorProduct Version RangeStatus
Cisco Cisco IOS XR Software 7.0.1 affected
7.1.1 affected
7.0.90 affected
6.7.1 affected
7.0.2 affected
7.1.15 affected
7.1.2 affected
6.7.2 affected
… +45 more rows
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I. Basic Information for CVE-2026-76505

Vulnerability Information
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Vulnerability Title
Cisco IOS XR Software for ASR 9000 Series Routers IPv4 Unicast Packets Denial of Service Vulnerability
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Cisco Cisco IOS XR Software 7.0.1 -

II. Public POCs for CVE-2026-76505

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III. Intelligence Information for CVE-2026-76505

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Other References for CVE-2026-76505 (1)

Same Patch Batch · Cisco · 2026-10-21 · 34 CVEs total

CVE-2026-76466 9.8 CRITICAL Cisco Expressway Series Remote Code Execution Vulnerability
CVE-2026-76473 9.8 CRITICAL Cisco Unified Communications Products Hardening Release: October 2026 - Improper control o
CVE-2026-76474 9.8 CRITICAL Cisco Unified Communications Products Hardening Release: October 2026 - Improper Authentic
CVE-2026-76475 9.3 CRITICAL Cisco Unified Communications Products Hardening Release: October 2026 - Cross-site Scripti
CVE-2026-20043 9.0 CRITICAL Multiple Cisco Products Snort 3 Software Hardening Release: October 2026
CVE-2026-76477 8.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Injection Vulnerab
CVE-2026-76476 8.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Improper Input Val
CVE-2026-76478 8.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Improper Access Co
CVE-2026-76490 8.6 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Out-of-bounds Write Vul
CVE-2026-76524 7.8 HIGH Open Source Snort 3 Control Channel Socket Aribitrary Command Execution Vulnerability
CVE-2026-20291 7.8 HIGH Multiple Cisco Products Snort 3 Software Hardening Release: October 2026
CVE-2026-76479 7.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Path Traversal Vul
CVE-2026-76494 7.8 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Code Injection Vulnerab
CVE-2026-76495 7.8 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Incorrect Permission As
CVE-2026-76481 7.5 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Improper Check or
CVE-2026-76491 7.5 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Denial of Service Vulne
CVE-2026-76492 7.5 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - NULL Pointer Vulnerabil
CVE-2026-76493 7.5 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Uncaught Exception Vuln
CVE-2026-20356 7.5 HIGH Multiple Cisco Products Snort 3 Software Hardening Release: October 2026
CVE-2026-20236 7.5 HIGH Multiple Cisco Products Snort 3 Software Hardening Release: October 2026

Showing top 20 of 34 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Cisco IOS XR Software
Same vendor: Cisco
Same weakness: CWE-20

V. Comments for CVE-2026-76505

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