CVE-2021-26098Network attack vector

Session hijacking via predictable RPC identifiers

Published Aug 4, 2021 · Updated Oct 25, 2024

Insufficient randomness in Fortinet FortiSandbox before 4.0.0 allows remote authenticated users to predict valid RPC session IDs. The RPC API draws session identifiers from a small random-value space, making valid identifiers predictable from a few device-state details. An attacker needs authenticated access and several state details; successful prediction exposes another session but does not alter data or interrupt service.

CVSS severity7.5
High
EPSS probability0.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insufficient randomness in Fortinet FortiSandbox before 4.0.0 allows remote authenticated users to predict valid RPC session IDs. The RPC API draws session identifiers from a small random-value space, making valid identifiers predictable from a few device-state details. An attacker needs authenticated access and several state details; successful prediction exposes another session but does not alter data or interrupt service.

The record

CVE
CVE-2021-26098
Published
Aug 4, 2021
Updated
Oct 25, 2024
Vendor
Fortinet
Product
FortiSandbox
Classifications
CWE-330, T1550.004
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

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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=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

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
5.0FortinetCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N/E:P/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-330Use of Insufficiently Random Values
T1550.004Use Alternate Authentication Material: Web Session Cookie

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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