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NVD / CVE Program· CNA fortinet

CVE-2026-26248: A improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Fortinet FortiSandbox 5.0.0 through…

HighCVSS 8.8 · v3.1—No exploit No fix recorded

Noroxi assessment

Priority: Monitor (action score 35/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.55% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Fortinet FortiSandbox 5.0.0 through 5.0.5, FortiSandbox 4.4.0 through 4.4.8, FortiSandbox 4.2 all versions, FortiSandbox Cloud 5.0.4 through 5.0.5, FortiSandbox PaaS 5.0.4 through 5.0.5 may allow an unauthenticated attacker to perform an XSS attack via social engineering and crafted HTTP requests.

Published
Nov 10, 2026
Updated
Nov 11, 2026
EPSS
0.5% · 46th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CNA vs NVD score

NVD
—
CNA · fortinet
7.9
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-26248

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

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Limit the impact of XSS

This is a cross-site scripting (XSS) vulnerability. A well-configured Content-Security-Policy doesn't fix it, but greatly reduces its impact. Check your site's CSP and other security headers for free.

Check security headers

Versions reported by the vendor

Affected version ranges reported by the assigning authority (fortinet). Independent of NVD's CPE analysis and usually ahead of it.

  • Fortinet FortiSandbox

    • 5.0.0 and later · up to and including 5.0.5affected · semver
    • 4.4.0 and later · up to and including 4.4.8affected · semver
    • 4.2.1 and later · up to and including 4.2.8affected · semver

  • Fortinet FortiSandbox Cloud

    • 5.0.4 and later · up to and including 5.0.5affected · semver

  • Fortinet FortiSandbox PaaS

    • 5.0.4 and later · up to and including 5.0.5affected · semver

Same product

fortinet: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-39808A improper neutralization of special elements used in an os command ('os command injection') vulnerability in Fortinet FortiSandbox 4.4.0…KEV
    97Now
  • CVE-2026-25089A improper neutralization of special elements used in an os command ('os command injection') vulnerability in Fortinet FortiSandbox 5.0.0…KEV
    92Now
  • CVE-2026-39813A path traversal: '../filedir' vulnerability in Fortinet FortiSandbox 5.0.0 through 5.0.5, FortiSandbox 4.4.0 through 4.4.8 may allow…
    46Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-106170Oct 13, 2026 · An Uncaught Exception vulnerability [CWE-248] vulnerability in Fortinet FortiSandbox 5.2.0 through 5.2.1, FortiSandbox 5.0.0 through 5.0.6…
    19Monitor
  • ← EarlierCVE-2026-106172Oct 13, 2026 · A use of hard-coded cryptographic key vulnerability in Fortinet FortiSandbox 5.2.0 through 5.2.1, FortiSandbox 5.0.0 through 5.0.6…
    21Monitor
  • ← EarlierCVE-2026-107656Oct 26, 2026 · An authentication bypass using an alternate path or channel vulnerability in Fortinet FortiSandbox 5.0.0 through 5.0.6, FortiSandbox 4.4.0…
    39Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2025-52436273 days apartAn Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability [CWE-79] vulnerability in Fortinet…
    40Plan
  • CVE-2025-54353336 days apartAn Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability [CWE-79] vulnerability in Fortinet…
    26Monitor
  • CVE-2025-61886210 days apartAn Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability [CWE-79] vulnerability in Fortinet…
    21Monitor
  • CVE-2026-39812210 days apartA improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Fortinet FortiSandbox 5.0.0 through…
    19Monitor
  • CVE-2025-53608245 days apartAn Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability [CWE-79] vulnerability in Fortinet…
    19Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

nvd-secondary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

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Change log

  1. Exploit maturity— → none

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records