Cisco ASA/FTD DoS flaw exploited in wild
CERT-FR warns Cisco Secure Firewall ASA and FTD software have a remotely exploitable DoS vulnerability actively exploited in the wild.
Sourcecert.cyber.gouv.fr — open the original
What to check
- Applies to
- The 1 CVE named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation
- CISA lists CVE-2026-76418 as exploited in the wild.
CERT-FR issued an advisory regarding CVE-2026-76418, a vulnerability affecting Cisco Secure Firewall ASA and Secure FTD software that allows a remote attacker to cause a denial of service. Cisco has confirmed active exploitation of this flaw in the wild, making it an urgent patching priority for organizations running affected versions.
The vulnerability impacts a wide range of ASA software versions (9.16 and earlier through 9.24.x) and FTD software versions (7.0 through 7.7.x and 10.0.x/10.1.x), indicating broad exposure across Cisco firewall deployments. Given these products are typically deployed at network perimeters, a successful DoS attack could disrupt critical security and connectivity services for affected organizations.
CERT-FR directs administrators to Cisco's security advisory (cisco-sa-asaftd-tunnel-dos-s6mgkb75, published October 28, 2026) for patch information. Given the active exploitation status, defenders running any of the listed ASA or FTD versions should prioritize immediate patching and review the Cisco bulletin for detection guidance and affected configuration details (reportedly tunnel-related).
Mentioned in this report
Source reporting: https://www.cert.cyber.gouv.fr/avis/CERTFR-2026-AVI-1412
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