[NEW] [high] Cisco ASA (Adaptive Security Appliance) and Secure Firewall Threat Defense: Vulnerability enables denial of service
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
A remote, anonymous attacker can exploit a vulnerability in Cisco ASA (Adaptive Security Appliance) and Cisco Secure Firewall Threat Defense to conduct a denial of service attack.
CSIRTS triage
- What
- A remote denial of service vulnerability allows anonymous attackers to disrupt service availability.
- Who is affected
- All deployments of Cisco ASA and Secure Firewall Threat Defense are affected.
- Urgency
- High; actively exploited in the wild, immediate mitigation required.
- Action
- Apply vendor security patches immediately or implement network-based mitigations to restrict attack vectors.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-2755
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Exploitation confirmedCVE-2026-20349Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 56% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-20349 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- highexploitedAL26-018 - Vulnerability affecting Cisco ASA and Secure Firewall Threat Defense Software Remote Access SSL VPN…cccs
- unknownexploitedNCSC-2026-0295 [1.00] [M/H] Vulnerability patched in Cisco Secure Firewall ASA and FTD softwarencsc-nl
- unknownexploitedCisco security advisory (AV26-807)cccs
- unknownexploitedCisco Products Multiple Vulnerabilitieshkcert
- unknownexploitedVulnerability in Cisco products (August 12, 2026)cert-fr-avis
- highexploitedCVE-2026-20349: A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Securi…nvd
- highexploitedCisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SS…cisco-psirt
- highexploitedCISA Adds Three Known Exploited Vulnerabilities to Catalogcisa
- criticalexploitedCVE-2026-20349: Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FT…cisa-kev
Recent advisories for Cisco ASA
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- highexploitedAL26-018 - Vulnerability affecting Cisco ASA and Secure Firewall Threat Defense Software Remote Access SSL VPN…cccs · 2026-08-13
- unknownexploitedNCSC-2026-0295 [1.00] [M/H] Vulnerability patched in Cisco Secure Firewall ASA and FTD softwarencsc-nl · 2026-08-12
- highexploitedCVE-2026-20349: A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Securi…nvd · 2026-08-11
- criticalexploitedCVE-2026-20349: Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FT…cisa-kev · 2026-08-11
- unknownexploited[Update] Multiple vulnerabilities in Cisco ASA and FTD (September 25, 2025)cert-fr-alerte · 2025-09-25
- criticalexploitedCVE-2025-20362: Cisco Secure Firewall Adaptive Security (ASA) Appliance and Secure Firewall Threat Defense (FT…cisa-kev · 2025-09-25
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