CVE-2023-20072Network attack vector

Device reload via fragmented tunnel packet handling

Published Mar 23, 2023 · Updated Oct 28, 2024

Denial of service in Cisco IOS XE Software 17.9.1, 17.9.1a, and 17.9.1w allows remote attackers to reload devices via fragmented tunnel packets. The fragmentation handler improperly processes large fragmented packets for tunnel protocols such as GRE, triggering a system reload. Exploitation is unauthenticated but requires a configured tunnel interface and packets addressed to the device; transit traffic alone is insufficient.

CVSS severity8.6
High
EPSS probability0.98%
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 XE Software 17.9.1, 17.9.1a, and 17.9.1w allows remote attackers to reload devices via fragmented tunnel packets. The fragmentation handler improperly processes large fragmented packets for tunnel protocols such as GRE, triggering a system reload. Exploitation is unauthenticated but requires a configured tunnel interface and packets addressed to the device; transit traffic alone is insufficient.

The record

CVE
CVE-2023-20072
Published
Mar 23, 2023
Updated
Oct 28, 2024
Vendor
ClamAV
Product
Cisco IOS XE Software
Classifications
CWE-20, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 23, 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 XE Softwareversion=n/a

Published CVSS scores

8.6Cisco Systems, Inc.CVSS: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.

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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-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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