CVE-2023-20049Network attack vector

Line-card reset via malformed IPv4 BFD packets

Published Mar 9, 2023 · Updated Oct 28, 2024

Denial of service in Cisco IOS XR Software allows remote attackers to reset affected line cards with malformed IPv4 BFD packets. The hardware-offload path incorrectly handles malformed packets and triggers a line-card exception or hard reset, interrupting traffic while it reloads. Exposure requires IOS XR 64-bit on specified ASR 9000 hardware, BFD hardware offload enabled on a Lightspeed-class line card, and an active hardware BFD session.

CVSS severity8.6
High
EPSS probability1.05%
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 allows remote attackers to reset affected line cards with malformed IPv4 BFD packets. The hardware-offload path incorrectly handles malformed packets and triggers a line-card exception or hard reset, interrupting traffic while it reloads. Exposure requires IOS XR 64-bit on specified ASR 9000 hardware, BFD hardware offload enabled on a Lightspeed-class line card, and an active hardware BFD session.

The record

CVE
CVE-2023-20049
Published
Mar 9, 2023
Updated
Oct 28, 2024
Vendor
ClamAV
Product
Cisco IOS XR Software
Classifications
CWE-805, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 9, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 28, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS XR Softwareversion=n/a

Published CVSS scores

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

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-805Buffer Access with Incorrect Length Value
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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