CVE-2021-26096Network attack vector

Authenticated memory corruption via crafted shell arguments

Published Aug 4, 2021 · Updated Oct 25, 2024

Heap-based buffer overflows in the Fortinet FortiSandbox command shell before 4.0.0 allow remote authenticated users to alter memory. Multiple command-shell argument handlers write specifically crafted argument data beyond heap-buffer bounds; Fortinet has not identified the affected commands or functions. A valid authenticated command-shell session is required, and the published record limits the confirmed consequence to memory-content manipulation.

CVSS severity8.8
High
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Heap-based buffer overflows in the Fortinet FortiSandbox command shell before 4.0.0 allow remote authenticated users to alter memory. Multiple command-shell argument handlers write specifically crafted argument data beyond heap-buffer bounds; Fortinet has not identified the affected commands or functions. A valid authenticated command-shell session is required, and the published record limits the confirmed consequence to memory-content manipulation.

The record

CVE
CVE-2021-26096
Published
Aug 4, 2021
Updated
Oct 25, 2024
Vendor
Fortinet
Product
FortiSandbox
Classifications
CWE-787
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 25, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=FortiSandbox before 4.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Fortinet · FortiSandboxversion=FortiSandbox before 4.0.0

Published CVSS scores

6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.4FortinetCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L/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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo