High-severity improper access control in Cisco IOS XR — affects core network infrastructure used broadly by enterprises and service providers; can cause major outages or compromise.
CVE-2026-20279
Cisco IOS XR improper access control allowing unauthorized access/privilege escalation
Is CVE-2026-20279 being exploited?
Not confirmed. CVE-2026-20279 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.30% probability of exploitation in the next 30 days.
How severe is CVE-2026-20279?
CVE-2026-20279 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-20279?
Yes. A fix has been recorded for CVE-2026-20279. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-20279 affect?
CVE-2026-20279 affects Cisco IOS XR Software, Carrier/service-provider routers (NCS/ASR classes), Enterprise core routers running IOS XR. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-20279?
Apply Cisco IOS XR hardening updates immediately and restrict management plane access
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Improper access control enabling unauthorized access or privilege escalation to alter configs, execute commands, or expose data on IOS XR routers.
Immediate action required
- affected6.5.29
- affected7.0.1
- affected6.5.26
- affected6.5.25
- affected6.5.28
- affected6.5.90
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- affected6.7.35
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- affected6.5.33
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- affected7.9.2
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- affected7.9.21
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- affected7.5.52
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- affected7.8.23
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- affected6.5.35
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- affected6.5.351
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- affected24.3.30
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As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.