CVE-2024-20276

Device reload via crafted process-switched traffic

Published Mar 27, 2024 · Updated Aug 1, 2024

Denial of service in Cisco IOS 15.5(1)SY5 through 15.5(1)SY11 allows attackers on an adjacent network to reload Catalyst switches. The process-switching path improperly handles crafted traffic instead of safely rejecting it, causing the device to reload unexpectedly. Exposure requires Catalyst 6500 or 6800 hardware with Supervisor Engine 2T or 6T and port security, device classifier, or AAA enabled.

CVSS severity7.4
High
EPSS probability0.29%
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 15.5(1)SY5 through 15.5(1)SY11 allows attackers on an adjacent network to reload Catalyst switches. The process-switching path improperly handles crafted traffic instead of safely rejecting it, causing the device to reload unexpectedly. Exposure requires Catalyst 6500 or 6800 hardware with Supervisor Engine 2T or 6T and port security, device classifier, or AAA enabled.

The record

CVE
CVE-2024-20276
Published
Mar 27, 2024
Updated
Aug 1, 2024
Vendor
ClamAV
Product
Cisco IOS
Classifications
CWE-248, T1498
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 27, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 1, 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?

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

  1. Affected versionversion=15.5(1)SY10
  2. Affected versionversion=15.5(1)SY11
  3. Affected versionversion=15.5(1)SY5
  4. Affected versionversion=15.5(1)SY6
  5. Affected versionversion=15.5(1)SY7
  6. Affected versionversion=15.5(1)SY8
  7. Affected versionversion=15.5(1)SY9

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOSversion=15.5(1)SY10; version=15.5(1)SY11; version=15.5(1)SY5; version=15.5(1)SY6; version=15.5(1)SY7; version=15.5(1)SY8; version=15.5(1)SY9

Published CVSS scores

7.4CiscoCVSS:3.1/AV:A/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.

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

No observations available

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

Weakness, pattern, technique

CWE-248Uncaught Exception
T1498Network Denial of Service

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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