U.S. CISA adds CISCO Secure Firewall ASA and Secure FTD flaws to its Known Exploited Vulnerabilities catalog
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2025-20333 +1 in the same advisory: …20362 | Authenticated Buffer Overflow RCE in Cisco ASA/FTD VPN Web Server CVE-2025-20333 is a buffer overflow (CWE-120) in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) software, caused by improper validation of user-supplied input in HTTP(S) requests. An attacker who already holds valid VPN user credentials can trigger it by sending crafted HTTP(S) requests to the device's VPN web interface; the flaw is remotely exploitable over the network with low attack complexity and no user interaction. A successful exploit allows arbitrary code execution as root, possibly resulting in complete compromise of the firewall or VPN gateway. Any organization running Cisco ASA or FTD software with the VPN web server enabled is affected. Exploitation is confirmed in the wild: the CVE was added to CISA's KEV on 2025-09-25, EPSS assigns a 70.7% probability of exploitation within 30 days (99th percentile), and Cisco and the UK NCSC have warned of real-world attacks (including RayInitiator and LINE VIPER malware deployment) that chain this flaw with at least one companion Cisco vulnerability. Do: Inventory all ASA/FTD devices with the VPN web server reachable by users (especially internet-exposed ones) and upgrade to the fixed releases listed in the Cisco PSIRT advisory; where patching is delayed, apply Cisco's recommended mitigations and hunt for indicators of the reported attack chain (RayInitiator/LINE VIPER). Because exploitation requires valid VPN credentials, treat VPN user credentials on affected gateways as potentially compromised and force resets. US federal agencies must follow the mitigation steps in CISA Emergency Directive 25-03 and BOD 22-01 timelines for this KEV entry. | 9.9 group max | 71% | KEV |
| mass≈100,000–300,000 internet-exposed ASA/FTD VPN web servers (order of magnitude), within a multi-million-device installed base serving large VPN user populations |
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Pierluigi Paganini
September 25, 2025
U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds CISCO Secure Firewall ASA and Secure FTD flaws to its Known Exploited Vulnerabilities catalog.
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added CISCO Secure Firewall ASA and Secure FTD flaws to its Known Exploited Vulnerabilities (KEV) catalog.
CISA urges Federal Agencies to identify and mitigate potential compromise of Cisco devices.
“CISA is aware of an ongoing exploitation campaign by an advanced threat actor targeting Cisco Adaptive Security Appliances (ASA). The campaign is widespread and involves exploiting zero-day vulnerabilities to gain unauthenticated remote code execution on ASAs, as well as manipulating read-only memory (ROM) to persist through reboot and system upgrade.” states CISA’s emergency directive. “This activity presents a significant risk to victim networks. Cisco assesses that this campaign is connected to the ArcaneDoor activity identified in early 2024 and that this threat actor has demonstrated a capability to successfully modify ASA ROM at least as early as 2024. These zero-day vulnerabilities in the Cisco ASA platform are also present in specific versions of Cisco Firepower. “
Below are the descriptions for these flaws:
- CVE-2025-20362 – Cisco Secure Firewall Adaptive Security (ASA) Appliance and Secure Firewall Threat Defense (FTD) Missing Authorization Vulnerability: Cisco Secure Firewall Adaptive Security (ASA) Appliance and Secure Firewall Threat Defense (FTD) Software VPN Web Server contain a missing authorization vulnerability. This vulnerability could be chained with CVE-2025-20333.
- CVE-2025-20333 – Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow Vulnerability: Cisco Secure Firewall Adaptive Security (ASA) Appliance and Secure Firewall Threat Defense (FTD) Software VPN Web Server contain a buffer overflow vulnerability that allows for remote code execution. This vulnerability could be chained with CVE-2025-20362.
CISA’s Emergency Directive orders agencies to identify all Cisco ASA and Firepower devices, follow core dump analysis steps, and submit results by Sept 26, 2025. If compromised, devices must be isolated and impacted agencies must report the incidents. Agencies must update supported devices within strict deadlines, retire unsupported models, and report full inventories with actions taken by Oct 2, 2025.
According to Binding Operational Directive (BOD) 22-01: Reducing the Significant Risk of Known Exploited Vulnerabilities, FCEB agencies have to address the identified vulnerabilities by the due date to protect their networks against attacks exploiting the flaws in the catalog.
Experts also recommend that private organizations review the Catalog and address the vulnerabilities in their infrastructure.
CISA orders federal agencies to fix the vulnerabilities by September 26, 2025.
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