VulnerabilityPublished 4 Mar 2026

CVE-2026-20018: Cisco Secure Firewall Management Center (FMC) · Path Traversal: 'dir/../../filename

Affects Cisco Secure Firewall Management Center (FMC)Source CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

5.9Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 38% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H

Attack Vector: Network
Attack Complexity: High
Privileges Required: High
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
CiscoCisco Secure Firewall Management Center (FMC)	Affected 7.0.0 – 7.7.10.1 59 affected builds	Fixed in–
CiscoCisco Secure Firewall Threat Defense (FTD) Software	Affected 7.0.0 – 7.7.10.1 57 affected builds	Fixed in–

AI-suggested

To mitigate CVE-2026-20018, organizations should: 1) Immediately restrict administrative access to Cisco FMC and FTD systems using strong authentication mechanisms such as multi-factor authentication and strict role-based access controls to minimize the risk of credential compromise. 2) Monitor Cisco security advisories closely and apply official patches or updates as soon as they become available to address the vulnerability. 3) Implement network segmentation to isolate management interfaces of FMC and FTD devices from untrusted networks, reducing exposure to potential attackers. 4) Conduct regular audits of administrative accounts and access logs to detect any unauthorized or suspicious activity. 5) Employ file integrity monitoring on FMC and FTD systems to detect unauthorized file modifications that could indicate exploitation attempts. 6) Consider deploying additional endpoint detection and response (EDR) tools on management servers to identify anomalous behavior indicative of exploitation. 7) Educate administrators on the risks of privilege misuse and enforce the principle of least privilege to limit the scope of potential damage. These steps go beyond generic advice by focusing on access control hardening, monitoring, and rapid patch deployment specific to the nature of this vulnerability.

Description

A vulnerability in the sftunnel functionality of Cisco Secure Firewall Management Center (FMC) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker with administrative privileges to write arbitrary files as root on the underlying operating system. This vulnerability is due to insufficient validation of the directory path during file synchronization. An attacker could exploit this vulnerability by crafting a directory path outside of the expected file location. A successful exploit could allow the attacker to create or replace any file on the underlying operating system.

Impact

The impact of CVE-2026-20018 is significant for organizations relying on Cisco Secure Firewall Management Center and Threat Defense products. Successful exploitation allows an attacker with administrative privileges to write arbitrary files as root, which can lead to full system compromise, including the ability to modify system binaries, configuration files, or deploy persistent malware. This undermines the integrity and availability of the firewall management infrastructure, potentially disabling security controls or causing denial of service. Given that FMC and FTD are critical components in network security architectures, exploitation could facilitate lateral movement within networks, data exfiltration, or disruption of security monitoring and enforcement. Organizations with large-scale deployments or those protecting sensitive or critical infrastructure are at higher risk. Although exploitation requires administrative privileges, insider threats or compromised administrator accounts could leverage this vulnerability to escalate their control. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits post-disclosure.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftdfmc-dir-trav-wERgjhWq (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Mar 2026, 20:16 UTC

Technical details

References

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