CVE-2025-20149VulnerabilityPublished 24 Sep 2025

CVE-2025-20149: Cisco IOS · Classic Buffer Overflow

Affects Cisco IOSSource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Local
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: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
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 24 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 2026-10-25.

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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC 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

AI-suggested

1. Immediate inventory and identification of Cisco IOS and IOS XE devices running affected versions within the network. 2. Restrict CLI access strictly to trusted administrators and enforce strong authentication mechanisms, including multi-factor authentication, to reduce the risk of unauthorized local access. 3. Monitor and audit CLI access logs for unusual or unauthorized command execution attempts. 4. Apply Cisco-released patches or updates as soon as they become available; maintain close communication with Cisco security advisories for timely updates. 5. Implement network segmentation to isolate critical network devices and limit the potential impact of a compromised local account. 6. Employ role-based access control (RBAC) to minimize privileges granted to users, ensuring that low-privileged accounts cannot execute commands that trigger the vulnerability. 7. Consider deploying intrusion detection/prevention systems (IDS/IPS) that can detect anomalous CLI command patterns or device reload events. 8. Develop and test incident response plans specifically addressing network device DoS scenarios to ensure rapid recovery and minimal downtime.

Description

A vulnerability in the CLI of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, local attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to a buffer overflow. An attacker with a low-privileged account could exploit this vulnerability by using crafted commands at the CLI prompt. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

Impact

For European organizations, the impact of CVE-2025-20149 could be significant, especially for those relying heavily on Cisco network infrastructure for critical operations. The vulnerability enables an authenticated attacker with low privileges to cause device reloads, resulting in network outages or degraded service availability. This can disrupt business continuity, impact service-level agreements, and potentially affect critical sectors such as finance, telecommunications, healthcare, and government services. Since the vulnerability requires local authentication, the risk is heightened in environments where internal threat actors or compromised credentials exist. The broad range of affected IOS versions implies many legacy and current devices may be vulnerable, increasing the attack surface. Additionally, the scope of affected systems includes routers and switches that form the backbone of enterprise and service provider networks, meaning exploitation could have cascading effects on network stability and security monitoring capabilities. Although no confidentiality or integrity impacts are reported, the availability disruption alone can have severe operational and reputational consequences for European entities.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-cli-EB7cZ6yO (opens in a new tab)

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 24 Sep 2025, 17:24 UTC

Technical details

References

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