Threat landscape
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Cisco Firewall Threat Defense, IOS XE und Meraki MX: Mehrere Schwachstellen

WID-SEC-2026-0041 · first 08.01.2026 · updated 29.01.2026 · CVSS 5,8

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What it is about

Snort ist ein freies Network Intrusion Prevention System (NIPS) und ein Network Intrusion Detection System (NIDS) der Firma Sourcefire. Cisco Secure Firewall Threat Defense ist eine Sicherheitslösung, die Funktionen wie Firewall, Intrusion Prevention und erweiterten Malware-Schutz in einer einzigen Appliance integriert. Cisco Internetwork Operating System (IOS) ist ein Betriebssystem, das für Cisco Geräte wie z. B. Router und Switches eingesetzt wird. Ein Angreifer kann mehrere Schwachstellen in Snort, Cisco Secure Firewall Threat Defense und Cisco IOS XE ausnutzen, um einen Denial of Service Angriff durchzuführen, und um Informationen offenzulegen.

Under what conditions?

The BSI does not name any particular preconditions. Exploitable remotely according to the BSI.

What can happen in the worst case

An attacker could use the vulnerability to

  • einen Denial of Service Angriff durchzuführen
  • Informationen offenzulegen

Am I affected?

Affected according to the BSI:

  • Open Source Snort <3.9.6.0
  • Cisco Secure Firewall Threat Defense <7.2.10.3 Hotfix
  • Cisco Secure Firewall Threat Defense <7.0.8.2 Hotfix
  • Cisco IOS XE <26.1.1
  • Cisco Meraki MX

The installed version is usually shown under “Help → About” or in the device’s admin interface.

What helps?

Update to at least:

  • Open Source Snort 3.9.6.0
  • Cisco Secure Firewall Threat Defense 7.2.10.3 Hotfix
  • Cisco Secure Firewall Threat Defense 7.0.8.2 Hotfix
  • Cisco IOS XE 26.1.1

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

CVE: CVE-2026-20026, CVE-2026-20027

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.

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