CVE-2026-59838: A improper neutralization of script-related html tags in a web page (basic xss) vulnerability in Fortinet Fort

Routine

MEDIUM 5.9UPGRADE

CVE-2026-59838 is a medium-severity flaw (CVSS 5.9) affecting fortisiem. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A improper neutralization of script-related html tags in a web page (basic xss) vulnerability in Fortinet FortiSIEM 7.4.0, FortiSIEM 7.3.0 through 7.3.4, FortiSIEM 7.2.0 through 7.2.6, FortiSIEM 7.1 all versions, FortiSIEM 7.0 all versions, FortiSIEM 6.7 all versions, FortiSIEM 6.6 all versions, FortiSIEM 6.5 all versions, FortiSIEM 6.4 all versions may allow attacker to execute unauthorized code or commands via <insert attack vector here>

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	Required
EPSS exploit chance	0.2% (top 85%)
CISA exploited list	No
Weakness	CWE-80
Published	2026-07-15
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

2026-07-15 14:18 UTCPublished CVE record published
2026-10-24 21:10 UTCUpdated Record last modified

fortinet fortisiem UPGRADE

Affected: >= 6.4.0 and < 7.2.7 · >= 7.3.0 and < 7.3.5 · 7.4.0

Fixed in: 7.2.7, 7.3.5

Safe to downgrade to: a release before 6.4.0

1. Check installed version

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

2. UPGRADE to 7.2.7 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade fortisiem

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 6.4.0 (Debian / Ubuntu)

apt-cache madison fortisiem sudo apt install fortisiem=<VERSION_BEFORE_6.4.0> sudo apt-mark hold fortisiem

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

dnf --showduplicates list fortisiem sudo dnf downgrade fortisiem-<VERSION_BEFORE_6.4.0> sudo dnf versionlock add fortisiem

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-2026-59838?

fortisiem: upgrade to 7.2.7, 7.3.5. Exact commands for each OS are on this page.

Is CVE-2026-59838 being exploited?

CVE-2026-59838 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-2026-59838 affect?

CVE-2026-59838 affects fortisiem. Severity is medium (CVSS 5.9). A improper neutralization of script-related html tags in a web page (basic xss) vulnerability in Fortinet FortiSIEM 7.4.0, FortiSIEM 7.3.0 through 7.3.4, FortiSIEM 7.2.0 through 7.2.6, FortiSIEM 7.1 all versions, FortiSIEM 7.0 all versions,

How urgent is CVE-2026-59838?

Priority 24/100. No elevated risk signals yet.

Software pages

Fortinet vulnerabilities

Related CVEs

CVE-2026-59841 HIGH 7.5 UPGRADE A improper restriction of communication channel to intended endpoints vulnerability in Fortinet FortiSIEMWindo
CVE-2026-70467 LOW 3.8 UPGRADE A server-side request forgery (ssrf) vulnerability in Fortinet FortiSIEM 7.5.0, FortiSIEM 7.4.0 through 7.4.2,

References

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