CVE intelligence and bounded remediation

CVE-2023-20027 — Cisco Ios Xe security vulnerability

High CVSS 8.6

A vulnerability in the implementation of the IPv4 Virtual Fragmentation Reassembly (VFR) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper reassembly of large packets that occurs when VFR is enabled on either a tunnel interface or on a physical interface that is configured with a maximum transmission unit (MTU) greater than 4,615 bytes. An attacker could exploit this vulnerability by sending fragmented packets through a VFR-enabled interface on an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

Severity
High
CVSS
8.6 (3.1)
Published
2023-03-23
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-416

Affected products

  • cisco / ios_xe / 3.9.0as
  • cisco / ios_xe / 3.9.1s
  • cisco / ios_xe / 3.9.2s
  • cisco / ios_xe / 3.10.0s
  • cisco / ios_xe / 3.10.1s
  • cisco / ios_xe / 3.10.2as

Showing 6 representative product identities from 190 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Use-after-free, double free, and expired resource use

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Trace ownership, references, callbacks, asynchronous tasks, and teardown paths around the affected object or resource.
  • Identify reachable inputs and timing or state transitions that can release the object while references remain.
  • Confirm affected builds, allocators, feature flags, architectures, and process privileges.

Remediate safely

  • Apply the maintained ownership or lifetime fix and rebuild all artifacts containing the affected native code.
  • Use explicit ownership, safe reference management, cancellation and join semantics, and idempotent teardown.
  • Add deterministic lifetime tests plus isolated sanitizer and concurrency coverage for shutdown and error paths.

Authoritative sources

Complete CVE record and remediation plan

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