CVE intelligence and bounded remediation

CVE-2023-20042 — Cisco Firepower Threat Defense security vulnerability

High CVSS 8.6

A vulnerability in the AnyConnect SSL VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to an implementation error within the SSL/TLS session handling process that can prevent the release of a session handler under specific conditions. An attacker could exploit this vulnerability by sending crafted SSL/TLS traffic to an affected device, increasing the probability of session handler leaks. A successful exploit could allow the attacker to eventually deplete the available session handler pool, preventing new sessions from being established and causing a DoS condition.

Severity
High
CVSS
8.6 (3.1)
Published
2023-11-01
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-404

Affected products

  • cisco / firepower_threat_defense / 7.0.0
  • cisco / firepower_threat_defense / 7.0.0.1
  • cisco / firepower_threat_defense / 7.0.1
  • cisco / firepower_threat_defense / 7.0.1.1
  • cisco / firepower_threat_defense / 7.0.2
  • cisco / firepower_threat_defense / 7.0.2.1

Showing 6 representative product identities from 51 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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