CVE-2020-3259 Vulnerability
Published: 11/21/2025
Written by: Lizzie Danielson
What is CVE-2020-3259 vulnerability?
CVE-2020-3259 is a vulnerability in the Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) software, classified as an information disclosure issue. It allows attackers to exploit improperly configured interfaces to gain unauthorized access to sensitive data. This vulnerability has a Common Vulnerability Scoring System (CVSS) score of 7.5, making it a high-severity threat. It directly impacts the confidentiality of affected systems by enabling attackers to retrieve system files.
When was it discovered?
CVE-2020-3259 was disclosed publicly on September 9, 2020. The vulnerability was identified and patched by Cisco’s Product Security Incident Response Team (PSIRT). Initial discoveries highlighted the flaw's potential for exposure, emphasizing its risk for enterprise users relying on ASA and FTD solutions.
Affected products & versions
Product | Versions Affected | Fixed Versions / Patch Links |
Cisco ASA Software | 9.8 through 9.12 | Version 9.13 |
Cisco Firepower Threat Defense (FTD) | Prior to version 6.6.4 | Version 6.6.5 |
CVE-2020-3259 technical description
The root cause of CVE-2020-3259 lies in the improper handling of HTTP requests in the affected Cisco products. Specifically, a flaw in the web services interface allowed attackers to request specific HTTPS resources without proper authentication. This flaw results from logic errors in the interface and a lack of access control settings.
Tactics, Techniques & Procedures (TTPs)
The vulnerability is exploited through unauthorized HTTPS requests crafted to bypass authentication controls. Attackers can enumerate data, such as system configurations or credentials, that reside on the web services module of the ASA/FTD devices.
Indicators of compromise
Unfamiliar HTTPS request patterns in logs
Connections from known malicious IP addresses
Retrieval of unexpected or sensitive data from ASA or FTD devices
Known proof-of-concepts & exploits
Multiple proof-of-concept exploits for CVE-2020-3259 are publicly available in major vulnerability research forums. Active exploitation has been observed, with attackers targeting enterprise environments using outdated ASA/FTD versions. No evidence suggests its integration into widespread malware campaigns as of recent findings.
How to detect CVE-2020-3259 vulnerability?
Detecting CVE-2020-3259 involves monitoring server logs for irregular HTTPS requests and cross-referencing against Indicators of Compromise (IOCs). Organizations should configure their Security Information and Event Management (SIEM) systems to flag unauthorized attempts on ASA or FTD devices. Regularly reviewing configuration audits and applying host-based IDS signatures can further aid detection.
Impact & risk of CVE-2020-3259 vulnerability
CVE-2020-3259 poses significant risks to enterprises by potentially exposing sensitive data such as credentials, configurations, and system details. Exploiting this vulnerability could undermine data confidentiality and operational security, paving the way for further breaches. A misuse scenario could involve an attacker leveraging disclosed configuration data for advanced persistent threats (APTs), such as lateral movement or privilege escalation.
Mitigation & remediation strategies
Organizations should immediately upgrade affected products to the latest patched versions of Cisco ASA and FTD software. If patching is not feasible, disabling the HTTPS web services interface and segregating sensitive network segments offer temporary mitigation strategies. Finally, applying access control measures to minimize exposure to untrusted sources is critical until permanent fixes are applied.
CVE-2020-3259 Vulnerability FAQs
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