VulnerabilityPublished 4 Mar 2026

CVE-2026-20013: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software · Memory Leak

Affects Cisco Secure Firewall Adaptive Security Appliance (ASA) 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: 0.3% chance of exploitation in 30 days – higher than 25% 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 Adaptive Security Appliance (ASA) Software	Affected 9.12.1 – 9.23.1.7 149 affected builds	Fixed in–
CiscoCisco Secure Firewall Threat Defense (FTD) Software	Affected 6.4.0 – 7.7.10.1 75 affected builds	Fixed in–

AI-suggested

Apply Cisco's security patches or software updates that address this vulnerability as soon as they become available. Regularly check Cisco's advisories for updates related to CVE-2026-20013.
If immediate patching is not feasible, implement network-level mitigations such as filtering or rate-limiting IKEv2 traffic from untrusted or external sources to reduce the risk of exploitation.
Monitor firewall logs and network traffic for unusual or excessive IKEv2 packet activity that could indicate attempted exploitation.
Employ intrusion detection and prevention systems (IDS/IPS) with signatures or heuristics targeting anomalous IKEv2 traffic patterns.
Segment and isolate critical firewall infrastructure to limit the blast radius of potential DoS attacks.
Maintain robust incident response plans to quickly reload or recover affected devices if a DoS condition occurs.
Conduct regular vulnerability assessments and penetration testing focused on VPN and firewall components to identify and remediate similar issues proactively.
Educate network security teams about this vulnerability and ensure they understand the importance of timely patch management and traffic monitoring for IKEv2 protocols.

Description

A vulnerability in the IKEv2 feature of Cisco Secure Firewall ASA Software and Cisco Secure FTD Software could allow an unauthenticated, remote attacker to cause a DoS condition on an affected device that may also impact the availability of services to devices elsewhere in the network. This vulnerability is due to memory exhaustion caused by not freeing memory during IKEv2 packet processing. An attacker could exploit this vulnerability by sending crafted IKEv2 packets to an affected device. A successful exploit could allow the attacker to exhaust resources, causing a DoS condition that will eventually require the device to manually reload.

Impact

The primary impact of CVE-2026-20013 is a denial-of-service condition on Cisco Secure Firewall ASA and FTD devices, which are widely deployed in enterprise and service provider networks globally. Successful exploitation can exhaust memory resources, causing the firewall to become unresponsive and disrupt network traffic filtering and VPN services. This can lead to significant downtime, loss of network availability, and potential disruption of critical business operations reliant on secure connectivity. The DoS condition may also affect other devices and services downstream by interrupting traffic flows or security enforcement. While the vulnerability does not compromise data confidentiality or integrity, the loss of firewall availability can expose networks to additional risks, such as unfiltered traffic or delayed incident response. Organizations relying on Cisco ASA for perimeter defense, VPN termination, or segmentation may experience operational impacts and increased risk exposure until the vulnerability is remediated. The ease of exploitation without authentication increases the threat level, especially in environments exposed to untrusted networks.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ikev2-dos-eBueGdEG (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Mar 2026, 20:05 UTC

Technical details

References

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