CVE-2020-12819Network attack vector

Authenticated daemon crash via oversized LCP packet

Published Dec 19, 2024 · Updated Dec 20, 2024

Heap-based buffer overflow in FortiOS 5.6.12, 6.0.10, 6.2.4, and 6.4.1 and earlier allows remote authenticated users to crash the SSL VPN daemon. The daemon mishandles an oversized Link Control Protocol packet and overflows heap memory during LCP message processing. Exploitation requires valid SSL VPN credentials and tunnel mode; daemon termination is demonstrated, while code execution is theoretical and described as practically very difficult.

CVSS severityUnavailable
Unscored
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in FortiOS 5.6.12, 6.0.10, 6.2.4, and 6.4.1 and earlier allows remote authenticated users to crash the SSL VPN daemon. The daemon mishandles an oversized Link Control Protocol packet and overflows heap memory during LCP message processing. Exploitation requires valid SSL VPN credentials and tunnel mode; daemon termination is demonstrated, while code execution is theoretical and described as practically very difficult.

The record

CVE
CVE-2020-12819
Published
Dec 19, 2024
Updated
Dec 20, 2024
Vendor
Fortinet
Product
FortiOS
Classifications
CWE-122, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 19, 2024CVE publishedPublication date reported by the CVE source.
  2. Dec 20, 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=5.6.0 <=5.6.12
  2. Affected versionversion=6.0.0 <=6.0.10
  3. Affected versionversion=6.2.0 <=6.2.4
  4. Affected versionversion=6.4.0 <=6.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Fortinet · FortiOSversion=5.6.0 <=5.6.12; version=6.0.0 <=6.0.10; version=6.2.0 <=6.2.4; version=6.4.0 <=6.4.1

Published CVSS scores

5.4FortinetCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L/E:U/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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
T1499.004Endpoint Denial of Service: Application 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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