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


- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 21 Oct 2026
- **Updated:** 22 Oct 2026
- **Also known as:** GHSA-5c8p-wwqr-9h22

## What is CVE-2026-76505?

CVE-2026-76505 is a high-severity vulnerability in Cisco IOS XR Software, published on 21 Oct 2026. 

### Official 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.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-76505?


## How do I fix CVE-2026-76505?

No fix has been published for CVE-2026-76505 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-76505 being exploited?

There is no known exploitation of CVE-2026-76505 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-76505 and fix it if it is affected.

What it is: CVE-2026-76505 is a high-severity vulnerability in Cisco IOS XR Software, published on 21 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-76505 in the wild and no public exploit code.

Affected product: Cisco IOS XR Software. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-76505/ (Markdown: https://insights.sbomify.com/CVE-2026-76505/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-76505
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-76505
- OSV: https://osv.dev/vulnerability/CVE-2026-76505

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-76505/
Summaries are generated and may contain mistakes; the official description above is the record.