Description
A vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a memory handling error when GRE over IPv6 traffic is processed. An attacker could exploit this vulnerability by sending crafted GRE over IPv6 packets with either IPv4 or IPv6 payload through an affected device. A successful exploit could allow the attacker to cause the device to crash, resulting in a DoS condition.
Affected products
cisco: secure firewall threat defense; cisco: asa 5505 firmware; cisco: asa 5505; cisco: asa 5510 firmware; cisco: asa 5510; cisco: asa 5512-x firmware; cisco: asa 5512-x; cisco: asa 5515-x firmware; cisco: asa 5515-x; cisco: asa 5520 firmware; cisco: asa 5520; cisco: asa 5525-x firmware; cisco: asa 5525-x; cisco: asa 5540 firmware; cisco: asa 5540
References2
- tools.cisco.com/security/center/content/CiscoSecurityAdvisory/c… Vendor Advisory
- tools.cisco.com/security/center/content/CiscoSecurityAdvisory/c… Vendor Advisory
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 2% percentile: 81 · as of 11 November 2026
- CWE
- CWE-415
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.