CVE-2025-20316VulnerabilityPublished 24 Sep 2025

CVE-2025-20316: Cisco IOS XE Software · Improper Access Control

Affects Cisco IOS XE SoftwareSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 07:57 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 26% 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:U/C:N/I:L/A:N

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

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: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

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 2026-10-26.

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

Affected software

Product	Affected	Fixed in
Cisco Cisco IOS XE Software	Affected =17.7.1 =17.10.1 =17.8.1 =17.9.1 =17.9.2 =17.9.3 =17.9.4 =17.9.5 =17.9.6 =17.9.7 =17.11.1 =17.12.1 =17.12.2 =17.12.3 =17.12.4 =17.12.5 =17.13.1 =17.14.1 =17.15.1 =17.15.2 =17.15.3 =17.16.1 =17.17.1	Fixed in–

AI-suggested

To mitigate CVE-2025-20316, European organizations should prioritize the following actions: 1) Upgrade affected Cisco IOS XE Software versions to patched releases as soon as Cisco publishes them. 2) Implement network segmentation and monitoring to detect abnormal MAC address table flushing or flooding events, which may indicate exploitation attempts. 3) Configure port security features on switches to limit the number of MAC addresses learned per port, reducing the risk of MAC table exhaustion. 4) Employ dynamic ARP inspection and DHCP snooping to prevent MAC spoofing and reduce the attack surface. 5) Use network anomaly detection systems to identify unusual traffic patterns consistent with flooding attacks. 6) Review and tighten ACL configurations to ensure minimal necessary permissions and consider additional filtering at upstream devices. 7) Conduct regular security audits and penetration testing focused on network infrastructure to identify potential exploitation paths. These measures go beyond generic patching advice by focusing on proactive detection and limiting the conditions that enable the vulnerability to be exploited.

Description

A vulnerability in the access control list (ACL) programming of Cisco IOS XE Software for Cisco Catalyst 9500X and 9600X Series Switches could allow an unauthenticated, remote attacker to bypass a configured ACL on an affected device. This vulnerability is due to the flooding of traffic from an unlearned MAC address on a switch virtual interface (SVI) that has an egress ACL applied. An attacker could exploit this vulnerability by causing the VLAN to flush its MAC address table. This condition can also occur if the MAC address table is full. A successful exploit could allow the attacker to bypass an egress ACL on an affected device.

Impact

For European organizations, this vulnerability poses a significant risk to the integrity of network segmentation and traffic filtering controls. Cisco Catalyst 9500X and 9600X Series Switches are widely deployed in enterprise and service provider networks across Europe, often forming the backbone of campus and data center networks. An attacker exploiting this vulnerability could bypass egress ACLs, potentially allowing unauthorized traffic flows that violate organizational security policies. This could facilitate lateral movement by threat actors inside corporate networks, data exfiltration, or the introduction of malicious traffic that would normally be blocked. The impact is particularly critical in sectors with stringent data protection requirements such as finance, healthcare, and government, where unauthorized data flows can lead to regulatory non-compliance and data breaches. Additionally, since the vulnerability does not require authentication or user interaction, it lowers the barrier for attackers to exploit it remotely. Although availability is not directly impacted, the integrity compromise of ACL enforcement can undermine trust in network security controls, increasing the risk of further attacks or data leakage.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cat9k-acl-L4K7VXgD (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Sep 2025, 17:22 UTC

Technical details

References

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