CVE-2018-15443
A vulnerability in the detection engine of Cisco Firepower System Software could allow an unauthenticated, remote attacker to bypass a configured Intrusion Prevention System (IPS) rule that inspects certain types of TCP traffic.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.77%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
A vulnerability in the detection engine of Cisco Firepower System Software could allow an unauthenticated, remote attacker to bypass a configured Intrusion Prevention System (IPS) rule that inspects certain types of TCP traffic. The vulnerability is due to incorrect TCP retransmission handling. An attacker could exploit this vulnerability by sending a crafted TCP connection request through an affected device. A successful exploit could allow the attacker to bypass configured IPS rules and allow uninspected traffic onto the network.
- CVSS 3.0
- 7.5 HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- EPSS
- 2.77% probability · 86th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-400
- Affected
- cisco/firepower system software
- Source
- psirt@cisco.com
EPSS 2.8% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://www.securityfocus.com/bid/105870Third Party Advisory, VDB Entry
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181107-fde-tcp-bypassVendor Advisory
- http://www.securityfocus.com/bid/105870Third Party Advisory, VDB Entry
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181107-fde-tcp-bypassVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.