CVE intelligence and bounded remediation

CVE-2022-20849 — Cisco Ios Xr security vulnerability

Medium CVSS 6.1

A vulnerability in the Broadband Network Gateway PPP over Ethernet (PPPoE) feature of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause the PPPoE process to continually crash. This vulnerability exists because the PPPoE feature does not properly handle an error condition within a specific crafted packet sequence. An attacker could exploit this vulnerability by sending a sequence of specific PPPoE packets from controlled customer premises equipment (CPE). A successful exploit could allow the attacker to cause the PPPoE process to continually restart, resulting in a denial of service condition (DoS).Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.This advisory is part of the September 2022 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see .

Severity
Medium
CVSS
6.1 (3.1)
Published
2024-11-15
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-391

Affected products

  • cisco / ios_xr / 6.5.1
  • cisco / ios_xr / 6.5.2
  • cisco / ios_xr / 6.5.3
  • cisco / ios_xr / 6.5.15
  • cisco / ios_xr / 6.6.1
  • cisco / ios_xr / 6.6.2

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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