VulnerabilityPublished 4 Mar 2026

CVE-2026-20052: Cisco Secure Firewall Threat Defense (FTD) Software · Access of Memory Location After End of Buffer

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

Compare

Not known to be exploited · CVSS 5.8 Medium.

Data as of 30 Oct 2026, 06:59 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 38% 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 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 Threat Defense (FTD) Software	Affected 7.4.0 – 7.6.0 6 affected builds	Fixed in–

AI-suggested

To mitigate CVE-2026-20052, organizations should: 1) Monitor Cisco's official security advisories and promptly apply any patches or updates released for affected FTD versions. 2) If patches are not yet available, consider temporarily disabling or limiting Snort 3 SSL packet inspection features to reduce exposure, balancing security needs and risk. 3) Implement network segmentation and strict access controls to limit exposure of Cisco FTD devices to untrusted networks, reducing the attack surface. 4) Employ anomaly detection and monitoring to identify unusual SSL traffic patterns that could indicate exploitation attempts. 5) Use redundant or failover firewall configurations to maintain security coverage during potential Snort 3 engine restarts. 6) Conduct regular backups and have incident response plans ready to quickly recover from potential DoS events. 7) Engage with Cisco support for guidance on workarounds or configuration changes that can mitigate the vulnerability until patches are available. These steps go beyond generic advice by focusing on specific features (Snort 3 SSL inspection) and operational continuity strategies.

Description

A vulnerability in the memory management handling for the Snort 3 Detection Engine of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart. This vulnerability is due to a logic error in memory management when a device is performing Snort 3 SSL packet inspection. An attacker could exploit this vulnerability by sending crafted SSL packets through an established connection to be parsed by the Snort 3 Detection Engine. A successful exploit could allow the attacker to cause a denial of service (DoS) condition when the Snort 3 Detection Engine unexpectedly restarts.

Impact

The primary impact of CVE-2026-20052 is a denial of service condition caused by the unexpected restart of the Snort 3 Detection Engine within Cisco Secure Firewall Threat Defense software. This can lead to temporary loss of intrusion detection and prevention capabilities, reducing the effectiveness of network security defenses. Organizations relying on Cisco FTD for perimeter security, threat detection, and SSL inspection may experience service disruptions, potentially allowing malicious traffic to pass undetected during the downtime. While the vulnerability does not directly expose sensitive data or allow unauthorized access, the interruption in security monitoring could be leveraged by attackers to conduct further attacks or data exfiltration. Critical infrastructure, financial institutions, government agencies, and large enterprises that depend on Cisco FTD for network security are particularly at risk of operational impact. The ease of exploitation (no authentication or user interaction required) increases the likelihood of opportunistic attacks, especially in environments with high volumes of SSL traffic. However, the lack of known exploits in the wild and the medium severity rating indicate that the threat is moderate but should not be underestimated.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-snort3ssl-FBEKYXpH (opens in a new tab)

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

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

Technical details

References

Community reviews

Related threats