CVE intelligence and bounded remediation

CVE-2017-3859 — Cisco Ios Xe security vulnerability

High CVSS 7.8

A vulnerability in the DHCP code for the Zero Touch Provisioning feature of Cisco ASR 920 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to a format string vulnerability when processing a crafted DHCP packet for Zero Touch Provisioning. An attacker could exploit this vulnerability by sending a specially crafted DHCP packet to an affected device. An exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition. This vulnerability affects Cisco ASR 920 Series Aggregation Services Routers that are running an affected release of Cisco IOS XE Software (3.13 through 3.18) and are listening on the DHCP server port. By default, the devices do not listen on the DHCP server port. Cisco Bug IDs: CSCuy56385.

Severity
High
CVSS
7.8 (2.0)
Published
2017-03-22
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-134

Affected products

  • cisco / ios_xe / 3.13.4s
  • cisco / ios_xe / 3.13.5as
  • cisco / ios_xe / 3.13.5s
  • cisco / ios_xe / 3.13.6as
  • cisco / ios_xe / 3.13.6s
  • cisco / ios_xe / 3.14.3s

Showing 6 representative product identities from 33 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Resource exhaustion and denial of service

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

Check exposure

  • Identify attacker-influenced work factors including input size, nesting, compression, fan-out, regex cost, allocation, recursion, retries, and connection lifetime.
  • Map per-request and shared CPU, memory, disk, descriptor, thread, queue, and downstream-service limits.
  • Determine whether authentication, tenancy, quotas, and rate controls apply before expensive processing begins.

Remediate safely

  • Bound input size, nesting, expansion, work, concurrency, queue depth, retries, and execution time before resource-intensive processing.
  • Release resources on every success, error, cancellation, and timeout path and use backpressure instead of unbounded buffering.
  • Update affected components and add small deterministic tests that assert resource ceilings rather than exhausting a host.

Authoritative sources

Complete CVE record and remediation plan

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