VulnerabilityPublished 10 Sep 2025

CVE-2025-20159: Cisco IOS XR Software · Improper Access Control

Affects Cisco IOS XR SoftwareSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 10:12 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 10 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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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
Cisco Cisco IOS XR Software	Affected 6.5.1 – 25.1.2 74 affected builds	Fixed in–

AI-suggested

Organizations should immediately audit their Cisco IOS XR devices to identify affected versions and prioritize remediation. Although no patches are currently available, mitigating controls include: 1) Restricting management interface access to trusted IP addresses using out-of-band management networks or dedicated management VLANs to reduce exposure. 2) Implementing additional network segmentation and firewall rules to limit access to management interfaces. 3) Employing strong monitoring and anomaly detection on management traffic to detect unauthorized access attempts. 4) Disabling unused management protocols (SSH, NetConf, gRPC) if not required. 5) Applying Cisco's recommended security best practices for IOS XR devices, including role-based access control and multi-factor authentication where possible. Organizations should monitor Cisco advisories closely for patches or updates addressing this vulnerability and plan for timely deployment once available. Additionally, conducting penetration testing focused on management interface ACLs can help validate the effectiveness of mitigations.

Description

A vulnerability in the management interface access control list (ACL) processing feature in Cisco IOS XR Software could allow an unauthenticated, remote attacker to bypass configured ACLs for the SSH, NetConf, and gRPC features. This vulnerability exists because management interface ACLs have not been supported on Cisco IOS XR Software Packet I/O infrastructure platforms for Linux-handled features such as SSH, NetConf, or gRPC. An attacker could exploit this vulnerability by attempting to send traffic to an affected device. A successful exploit could allow the attacker to bypass an ingress ACL that is applied on the management interface of the affected device.

Impact

For European organizations, this vulnerability poses a significant risk to network infrastructure security. Cisco IOS XR is widely deployed in service provider and enterprise core networks across Europe, managing critical routing and switching infrastructure. An attacker bypassing ACLs on management interfaces could gain unauthorized access to management protocols like SSH, NetConf, or gRPC, potentially allowing them to manipulate device configurations or inject malicious commands. This could lead to network integrity issues, unauthorized configuration changes, and potential lateral movement within the network. While the vulnerability does not directly impact confidentiality or availability, the ability to bypass ACLs on management interfaces undermines network security controls and could facilitate further attacks. European telecom operators, ISPs, and large enterprises relying on Cisco IOS XR for backbone and edge routing are particularly at risk. The absence of authentication requirements and the remote exploitability increase the urgency for mitigation in critical infrastructure environments.

References

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

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Sep 2025, 16:12 UTC

Technical details

References

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