CVE intelligence and bounded remediation

CVE-2021-34705 — Cisco Ios security vulnerability

Medium CVSS 5.3

A vulnerability in the Voice Telephony Service Provider (VTSP) service of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to bypass configured destination patterns and dial arbitrary numbers. This vulnerability is due to insufficient validation of dial strings at Foreign Exchange Office (FXO) interfaces. An attacker could exploit this vulnerability by sending a malformed dial string to an affected device via either the ISDN protocol or SIP. A successful exploit could allow the attacker to conduct toll fraud, resulting in unexpected financial impact to affected customers.

Severity
Medium
CVSS
5.3 (3.1)
Published
2021-09-23
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-232

Affected products

  • cisco / ios / 12.3(7)xm
  • cisco / ios / 12.3(7)xr
  • cisco / ios / 12.3(7)xr1
  • cisco / ios / 12.3(7)xr2
  • cisco / ios / 12.3(7)xr3
  • cisco / ios / 12.3(7)xr4

Showing 6 representative product identities from 1721 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

General vulnerability remediation

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

Check exposure

  • Confirm the affected component, deployment paths, reachable interfaces, and enabled features from inventories and configuration, without probing production destructively.
  • Compare the advisory's affected conditions with the repository lockfiles, build manifests, artifacts, and runtime inventory.
  • Identify data sensitivity, trust boundaries, and privilege level for every confirmed affected deployment.

Remediate safely

  • Apply a vendor-supported fix or remove the affected component or feature; record the selected change and its source in the repository.
  • Update direct and transitive dependency locks, generated artifacts, deployment manifests, and asset inventories together.
  • Add a regression test for the documented unsafe condition using inert inputs and preserve rollback instructions.

Authoritative sources

Complete CVE record and remediation plan

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