dbcve.org
Ios XrOperating system · Cisco

CVE-2025-20142

HIGH · 8.6 CVSS v3.1 Published 2025-03-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the IPv4 access control list (ACL) feature and quality of service (QoS) policy feature of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers, ASR 9902 Compact High-Performance Routers, and ASR 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause a line card to reset, resulting in a denial of service (DoS) condition. This vulnerability is due to the incorrect handling of malformed IPv4 packets that are received on line cards where the interface has either an IPv4 ACL or QoS policy applied. An attacker could exploit this vulnerability by sending crafted IPv4 packets through an affected device. A successful exploit could allow the attacker to cause network processor errors, resulting in a reset or shutdown of the network process. Traffic over that line card would be lost while the line card reloads. Note: This vulnerability has predominantly been observed in Layer 2 VPN (L2VPN) environments where an IPv4 ACL or QoS policy has been applied to the bridge virtual interface. Layer 3 configurations where the interface has either an IPv4 ACL or QoS policy applied are also affected, though the vulnerability has not been observed.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A remote code execution vulnerability exists in the IPv4 ACL and QoS policy processing of Cisco IOS XR Software on ASR 9000 series routers. Malformed IPv4 packets sent to interfaces with IPv4 ACLs or QoS policies applied trigger network processor errors, causing line card resets and DoS conditions. The vulnerability predominantly affects L2VPN environments with ACLs/QoS on bridge virtual interfaces, though L3 configurations are also vulnerable.

MitigationApply Cisco's IOS XR software patches when available. As interim mitigation, remove IPv4 ACLs and QoS policies from affected bridge virtual interfaces (L2VPN) and Layer 3 interfaces until patching can be completed.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Ios XrOperating system
Affected:= 6.7.2= 6.7.3= 6.7.35= 6.8.1= 6.8.2= 6.9.1= 6.9.2= 7.1.2= 7.1.3= 7.1.15= 7.1.25= 7.3.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the Cisco IOS XR version
    Run 'show version' or 'admin show version' on the router and note the software release number
    Affected if The installed version is exactly 6.7.2, 6.7.3, 6.7.35, 6.8.1, 6.8.2, 6.9.1, 6.9.2, 7.1.2, 7.1.3, 7.1.15, 7.1.25, or 7.3.1
  2. Verify if IPv4 ACLs are applied to any interfaces
    Run 'show running-config interface' for each interface and look for 'ipv4 access-group' or 'access-list' applied in the configuration
    Affected if IPv4 ACLs are applied to any interface, particularly on bridge virtual interfaces (BVI) in L2VPN setups or Layer 3 interfaces
  3. Check for QoS policies on interfaces
    Run 'show policy-map interface' to list all interfaces with QoS policies applied, or review interface configurations for 'service-policy' statements
    Affected if QoS service policies are bound to interfaces, especially on bridge virtual interfaces or L3 interfaces
  4. Identify L2VPN bridge domain configurations
    Run 'show running-config | include bvi|bridge' or 'show l2vpn bridge-domain' to list bridge virtual interfaces configured
    Affected if The router has bridge virtual interfaces (BVI) configured in L2VPN bridge domains with ACLs or QoS applied
  5. Confirm line card type on ASR 9000
    Run 'show inventory' or 'admin show inventory' to identify the network processor line cards in use
    Affected if The router uses ASR 9000 series line cards and meets the affected version criteria in Steps 1-4

A router is affected if it runs one of the listed IOS XR versions AND has IPv4 ACLs or QoS policies applied to interfaces, especially bridge virtual interfaces in L2VPN environments or Layer 3 interfaces.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco's IOS XR software patches when available. As interim mitigation, remove IPv4 ACLs and QoS policies from affected bridge virtual interfaces (L2VPN) and Layer 3 interfaces until patching can be completed.

Fix this in Ios Xr Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-20142 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data