VulnerabilityPublished 4 Mar 2026

CVE-2026-20025: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software · Integer Overflow or Wraparound

Affects Cisco Secure Firewall Adaptive Security Appliance (ASA) SoftwareSource CVE Database V5

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Not known to be exploited · CVSS 6.8 Medium.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

6.8Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
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: 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 Adaptive Security Appliance (ASA) Software	Affected 9.12.1 – 9.23.1.13 156 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

To mitigate CVE-2026-20025, organizations should: 1) Apply Cisco’s security patches or software updates that address this vulnerability as soon as they become available, prioritizing devices running affected ASA and FTD versions. 2) Restrict OSPF adjacency to trusted devices only by enforcing strict authentication and network segmentation to limit exposure to untrusted or potentially compromised devices. 3) Regularly rotate and protect OSPF secret keys to reduce the risk of key compromise. 4) Monitor OSPF traffic for anomalous or malformed LSU packets that could indicate exploitation attempts. 5) Implement network access controls to prevent unauthorized devices from establishing adjacency with critical routers or firewalls. 6) Consider deploying redundant firewall and routing paths to maintain availability in case of device reloads. 7) Conduct regular security audits and vulnerability assessments of network devices to identify and remediate similar protocol-level weaknesses. These steps go beyond generic advice by focusing on OSPF-specific controls and operational best practices tailored to the nature of this vulnerability.

Description

A vulnerability in the OSPF protocol of Cisco Secure Firewall ASA Software and Cisco Secure FTD Software could allow an authenticated, adjacent attacker to cause an affected device to reload unexpectedly, resulting in a DoS condition. To exploit this vulnerability, the attacker must have the OSPF secret key. This vulnerability is due to insufficient input validation when processing OSPF link-state update (LSU) packets. An attacker could exploit this vulnerability by sending crafted OSPF LSU packets. A successful exploit could allow the attacker to corrupt the heap, causing the device to reload, resulting in a DoS condition.

Impact

The primary impact of CVE-2026-20025 is a denial-of-service condition caused by device reloads triggered by heap corruption. For organizations relying on Cisco Secure Firewall ASA or FTD devices for perimeter security and routing, this can lead to temporary loss of firewall and routing capabilities, potentially disrupting network traffic and security enforcement. The requirement for adjacency and possession of the OSPF secret key limits the risk to environments where OSPF is actively used and where the attacker can gain network proximity and authentication. However, in large enterprise or service provider networks where OSPF is common, an attacker who compromises a router or gains insider access could exploit this vulnerability to cause network outages or degrade service availability. This could impact critical infrastructure, financial institutions, government agencies, and other sectors relying on Cisco ASA devices for secure and reliable network operations. The lack of confidentiality or integrity impact reduces the risk of data breach or manipulation, but the availability impact can still cause significant operational disruption and potential cascading effects in complex network topologies.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ospf-ZH8PhbSW (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Mar 2026, 20:07 UTC

Technical details

References

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