VulnerabilityPublished 4 Mar 2026

CVE-2026-20058: Cisco Secure Firewall Threat Defense (FTD) Software · Access of Memory Location Before Start of Buffer

Affects Cisco Secure Firewall Threat Defense (FTD) SoftwareSource CVE Database V5

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Not known to be exploited · CVSS 5.8 Medium.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

5.8Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 35% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: None
Integrity: None
Availability: Low

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: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

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 30 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 Threat Defense (FTD) Software	Affected 7.2.0 – 7.7.10.1 37 affected builds	Fixed in–
CiscoCisco UTD SNORT IPS Engine Software	Affected 17.9.3a – 17.18.2 30 affected builds	Fixed in–

AI-suggested

Organizations should monitor Cisco's official security advisories for patches addressing CVE-2026-20058 and apply updates promptly to all affected FTD versions. In the interim, network administrators can implement strict ingress filtering to block suspicious or malformed VBA data packets targeting the Snort 3 Detection Engine. Deploying network segmentation to isolate critical firewall management interfaces can reduce exposure. Additionally, enabling logging and alerting on Snort engine crashes or restarts can provide early detection of exploitation attempts. Where feasible, consider temporarily disabling or restricting the VBA feature within Snort 3 if it is not essential to operational requirements. Regularly auditing firewall configurations and maintaining up-to-date threat intelligence feeds will help identify and mitigate related attack vectors. Finally, incorporating redundancy and failover mechanisms for firewall appliances can minimize operational impact during potential DoS events.

Description

Multiple Cisco products are affected by vulnerabilities in the Snort 3 VBA feature that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash. These vulnerabilities are due to improper error checking when decompressing VBA data. An attacker could exploit these vulnerabilities by sending crafted VBA data to the Snort 3 Detection Engine on the targeted device. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to unexpectedly restart, causing a DoS condition.

Impact

The primary impact of CVE-2026-20058 is a denial-of-service condition on Cisco Secure Firewall Threat Defense devices. By causing the Snort 3 Detection Engine to crash and restart, attackers can disrupt the firewall's ability to inspect and filter network traffic effectively. This disruption can lead to temporary loss of intrusion detection and prevention capabilities, potentially allowing other malicious activities to go unnoticed during the downtime. For organizations relying heavily on Cisco FTD for perimeter defense and threat detection, this could degrade their security posture and increase exposure to other attacks. Although the vulnerability does not allow data theft or system compromise directly, the availability impact can have cascading effects on network security monitoring and incident response. Large enterprises, service providers, and critical infrastructure operators using affected Cisco FTD versions are particularly at risk of operational disruption. The ease of remote exploitation without authentication further elevates the threat level, especially in hostile network environments.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-snort3-vbavuls-96UcVVed (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Mar 2026, 20:15 UTC

Technical details

References

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