CVE-2026-59835: A exposure of resource to wrong sphere vulnerability in Fortinet FortiSandbox 5.0.0 through 5.0.2, FortiSandbo

This month

HIGH 8.6REMOTEUPGRADE

CVE-2026-59835 is a high-severity flaw (CVSS 8.6) affecting fortisandbox. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A exposure of resource to wrong sphere vulnerability in Fortinet FortiSandbox 5.0.0 through 5.0.2, FortiSandbox 4.4.3 through 4.4.8 may allow an unauthenticated attacker to access the VNC server of VMs performing scanning via network requests.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 67%)
CISA exploited list	No
Weakness	CWE-668
Published	2026-07-14
Last modified	2026-10-24

Publisher (CNA): Fortinet, Inc. · Vendor: fortinet

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-14 16:17 UTCPublished CVE record published
2026-10-24 21:10 UTCUpdated Record last modified

fortinet fortisandbox UPGRADE

Affected: >= 4.4.3 and < 4.4.9 · >= 5.0.0 and < 5.0.3

Fixed in: 4.4.9, 5.0.3

Safe to downgrade to: a release before 4.4.3

1. Check installed version

apt-cache policy fortisandbox || rpm -q fortisandbox || fortisandbox --version

2. UPGRADE to 4.4.9 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade fortisandbox

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade fortisandbox

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.4.3 (Debian / Ubuntu)

apt-cache madison fortisandbox sudo apt install fortisandbox=<VERSION_BEFORE_4.4.3> sudo apt-mark hold fortisandbox

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list fortisandbox sudo dnf downgrade fortisandbox-<VERSION_BEFORE_4.4.3> sudo dnf versionlock add fortisandbox

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-59835?

fortisandbox: upgrade to 4.4.9, 5.0.3. Exact commands for each OS are on this page.

Is CVE-2026-59835 being exploited?

CVE-2026-59835 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-59835 affect?

CVE-2026-59835 affects fortisandbox. Severity is high (CVSS 8.6). A exposure of resource to wrong sphere vulnerability in Fortinet FortiSandbox 5.0.0 through 5.0.2, FortiSandbox 4.4.3 through 4.4.8 may allow an unauthenticated attacker to access the VNC server of VMs performing scanning via network reques

How urgent is CVE-2026-59835?

Priority 43/100. High severity; Remotely exploitable, no login, no user action

Software pages

Fortinet vulnerabilities

References

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