Cisco IOS XR: Schwachstelle ermöglicht Denial of Service
WID-SEC-2026-4108 · first 22.10.2026 · updated 22.10.2026 · CVSS 7,5
What it is about
Cisco Internetwork Operating System (IOS) ist ein Betriebssystem, das für Cisco Geräte wie z. B. Router und Switches eingesetzt wird. Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Cisco IOS XR ausnutzen, um einen Denial of Service Angriff durchzuführen.
Under what conditions?
Over the network and without logging in. This is the most dangerous combination: attackers can scan reachable devices automatically.
What can happen in the worst case
An attacker could use the vulnerability to
- einen Denial of Service Angriff durchzuführen
Am I affected?
Affected according to the BSI:
- Cisco IOS XR <7.9.2
- Cisco IOS XR <7.9.21
- Cisco IOS XR <7.10.2
- Cisco IOS XR <7.11.2
- Cisco IOS XR <7.11.21
- Cisco IOS XR <24.1.2
- Cisco IOS XR <24.2.2
- Cisco IOS XR <24.2.21
- Cisco IOS XR <24.3.2
- Cisco IOS XR <24.4.2
The installed version is usually shown under “Help → About” or in the device’s admin interface.
What helps?
Update to at least:
- Cisco IOS XR 7.9.2
- Cisco IOS XR 7.9.21
- Cisco IOS XR 7.10.2
- Cisco IOS XR 7.11.2
- Cisco IOS XR 7.11.21
- Cisco IOS XR 24.1.2
- Cisco IOS XR 24.2.2
- Cisco IOS XR 24.2.21
- Cisco IOS XR 24.3.2
- Cisco IOS XR 24.4.2
Is the vulnerability already being exploited?
None of the CVEs is in the CISA catalogue of exploited vulnerabilities. That does not mean there are no attacks, only that none are documented.
Information and sources
- Original BSI advisory (WID)
- Cisco Security Advisory cisco-sa-asr9k-tUyxcyXN vom 2026-10-21 sec.cloudapps.cisco.com
CVE: CVE-2026-76505
Source: BSI warning and information service (CERT-Bund); CISA. The assessment of the conditions is my reading of the BSI text; the external pages are in their original language.