CVE intelligence and bounded remediation

CVE-2024-20526 — Cisco Adaptive Security Appliance Software security vulnerability

Medium CVSS 5.3

A vulnerability in the SSH server of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition for the SSH server of an affected device. This vulnerability is due to a logic error when an SSH session is established. An attacker could exploit this vulnerability by sending crafted SSH messages to an affected device. A successful exploit could allow the attacker to exhaust available SSH resources on the affected device so that new SSH connections to the device are denied, resulting in a DoS condition. Existing SSH connections to the device would continue to function normally. The device must be rebooted manually to recover. However, user traffic would not be impacted and could be managed using a remote application such as Cisco Adaptive Security Device Manager (ASDM).

Severity
Medium
CVSS
5.3 (3.1)
Published
2024-10-23
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-400, CWE-770

Affected products

  • cisco / adaptive_security_appliance_software / 9.16.4.67
  • cisco / adaptive_security_appliance_software / 9.16.4.70
  • cisco / adaptive_security_appliance_software / 9.18.4.40
  • cisco / adaptive_security_appliance_software / 9.20.3

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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