--- title: "CVE-2025-20333: Buffer Copy without Checking Size of Input | CubePath" description: "A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD)…" language: en source: https://cubepath.com/security/cve/CVE-2025-20333 --- # CVE-2025-20333: Buffer Copy without Checking Size of Input | CubePath ## Description A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker to execute arbitrary code on an affected device. This vulnerability is due to improper validation of user-supplied input in HTTP(S) requests. An attacker with valid VPN user credentials could exploit this vulnerability by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to execute arbitrary code as root, possibly resulting in the complete compromise of the affected device. Official description from the CVE record, published by cisco. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2025-20333) ## Key data ### CVSS 3.1 Critical 9.9 Score published by cisco in the CVE record. CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H | Metric | Value | What it means | | ---------------------- | ------- | ----------------------------------------------------------------------------------- | | Attack vector | Network | The vulnerable component can be reached over a network, possibly from the Internet. | | Attack complexity | Low | No special conditions are needed. The attack can be repeated at will. | | Privileges required | Low | A basic user account is needed. | | User interaction | None | No action from any user is needed. | | Scope | Changed | The impact can reach other components beyond the vulnerable one. | | Confidentiality impact | High | Serious or total effect on the secrecy of data. | | Integrity impact | High | Serious or total effect on the trustworthiness of data. | | Availability impact | High | Serious or total effect on availability. | CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at [first.org/cvss](https://www.first.org/cvss/) . ### EPSS Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days. Score 0.72037 (72.0% probability) Percentile 99.4% Scores of Nov 10, 2026 Model v2026.06.15 ### CISA Known Exploited Vulnerabilities This CVE is listed in the CISA KEV catalog. Name in the catalog Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow Vulnerability Added to the catalog Sep 25, 2025 Federal due date Sep 26, 2025 ### CISA assessment as of Sep 26, 2025 Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA. Exploitation Recorded by CISA as active Automatable no Technical impact total ### Weakness (CWE) CWE catalog version 5.0. CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license. - [CWE-120](https://cwe.mitre.org/data/definitions/120.html) Buffer Copy without Checking Size of Input ## Affected products Products listed in the CVE record, as the CNA published them. - Cisco Secure Firewall Adaptive Security Appliance (ASA) Software - affected: 9.8.1 - affected: 9.8.1.5 - affected: 9.8.1.7 - affected: 9.8.2 - affected: 9.8.2.8 - affected: 9.8.2.14 - affected: 9.8.2.15 - affected: 9.8.2.17 - affected: 9.8.2.20 - affected: 9.8.2.24 - affected: 9.8.2.26 - affected: 9.8.2.28 - affected: 9.8.2.33 - affected: 9.8.2.35 - affected: 9.8.2.38 - affected: 9.8.3.8 - affected: 9.8.3.11 - affected: 9.8.3.14 - affected: 9.8.3.16 - affected: 9.8.3.18 - affected: 9.8.3.21 - affected: 9.8.3 - affected: 9.8.3.26 - affected: 9.8.3.29 - affected: 9.8.4 - and 181 more - Cisco Secure Firewall Threat Defense (FTD) Software - affected: 6.2.3 - affected: 6.2.3.1 - affected: 6.2.3.2 - affected: 6.2.3.3 - affected: 6.2.3.4 - affected: 6.2.3.5 - affected: 6.2.3.6 - affected: 6.2.3.7 - affected: 6.2.3.8 - affected: 6.2.3.10 - affected: 6.2.3.11 - affected: 6.2.3.9 - affected: 6.2.3.12 - affected: 6.2.3.13 - affected: 6.2.3.14 - affected: 6.2.3.15 - affected: 6.2.3.16 - affected: 6.2.3.17 - affected: 6.2.3.18 - affected: 6.6.0 - affected: 6.6.0.1 - affected: 6.6.1 - affected: 6.6.3 - affected: 6.6.4 - affected: 6.6.5 - and 69 more ## References Links listed in the CVE record. They lead to other sites, which CubePath does not control. - [cisco-sa-asaftd-webvpn-z5xP8EUB](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-webvpn-z5xP8EUB) (sec.cloudapps.cisco.com) ## Timeline 1. ID reserved Oct 10, 2024 2. Added to CISA KEV Sep 25, 2025 3. Record published Sep 25, 2025 4. Record last updated Feb 26, 2026 ## Look up another CVE ## About CubePath CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection. [Cloud VPS](https://cubepath.com/vps) [DDoS protection](https://cubepath.com/ddos-protection) Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 20:04 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)