CVE-2025-20146Network attack vector

Line-card reset via malformed IPv4 multicast packets

Published Mar 12, 2025 · Updated Mar 21, 2025

Denial of service in Cisco IOS XR Software on affected ASR 9000 routers allows remote attackers to reset a line card via IPv4 multicast traffic. The Layer 3 multicast path incorrectly handles malformed IPv4 multicast packets traversing a line card interface with an IPv4 ACL or QoS policy. Exposure requires Lightspeed or Lightspeed-Plus hardware, Layer 3 multicast or MVPN, and an ACL or QoS policy on the interface; exploitation interrupts traffic while the card reloads.

CVSS severity8.6
High
EPSS probability0.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Cisco IOS XR Software on affected ASR 9000 routers allows remote attackers to reset a line card via IPv4 multicast traffic. The Layer 3 multicast path incorrectly handles malformed IPv4 multicast packets traversing a line card interface with an IPv4 ACL or QoS policy. Exposure requires Lightspeed or Lightspeed-Plus hardware, Layer 3 multicast or MVPN, and an ACL or QoS policy on the interface; exploitation interrupts traffic while the card reloads.

The record

CVE
CVE-2025-20146
Published
Mar 12, 2025
Updated
Mar 21, 2025
Vendor
ClamAV
Product
Cisco IOS XR Software
Classifications
CWE-20, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 12, 2025CVE publishedPublication date reported by the CVE source.
  2. Mar 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=24.1.1
  2. Affected versionversion=24.1.2
  3. Affected versionversion=24.2.1
  4. Affected versionversion=24.2.2
  5. Affected versionversion=24.3.1
  6. Affected versionversion=24.3.2
  7. Affected versionversion=7.10.2
  8. Affected versionversion=7.11.1
  9. Affected versionversion=7.11.2
  10. Affected versionversion=7.11.21
  11. Affected versionversion=7.9.21

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS XR Softwareversion=24.1.1; version=24.1.2; version=24.2.1; version=24.2.2; version=24.3.1; version=24.3.2; version=7.10.2; version=7.11.1; version=7.11.2; version=7.11.21; version=7.9.21

Published CVSS scores

8.6CiscoCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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