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Cloud Security GatewayApplication · Forcepoint

CVE-2023-26291

MEDIUM · 6.1 CVSS v3.1 Published 2023-03-29
Fix available
A fix is available. Upgrade to 2023-03-29 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Forcepoint Cloud Security Gateway (CSG) Portal on Web Cloud Security Gateway, Email Security Cloud (login_form.mhtml modules), Forcepoint Web Security Portal on Hybrid (login_form.mhtml modules) allows Reflected XSS.This issue affects Cloud Security Gateway (CSG): before 03/29/2023; Web Security: before 03/29/2023.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Reflected XSS vulnerability in Forcepoint login_form.mhtml modules across Cloud Security Gateway Portal, Email Security Cloud, and Web Security Portal. Attackers can inject malicious scripts through the login form that get reflected back to users.

MitigationApply Forcepoint vendor patch released on or after 03/29/2023 to address input validation in login_form.mhtml modules.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Cloud Security GatewayApplication
Affected:< 2023-03-29
Web SecurityApplication
Affected:< 2023-03-29

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed Forcepoint product
    Access the admin console or check system documentation to determine if Forcepoint Cloud Security Gateway, Web Security, or Email Security Cloud is deployed
    Affected if Any of these products are installed without knowing the version
  2. Check the product version
    Locate the version information in the admin console, about page, or system files. Compare against the fixed release date of 2023-03-29
    Affected if Version is earlier than the March 29, 2023 patch release
  3. Verify login portal accessibility
    Attempt to access the login portal URL (typically /mhtml/login_form.mhtml or similar path) via a browser or curl request
    Affected if The login_form.mhtml module is accessible without authentication
  4. Check for XSS indicators in login form response
    Send a test request with a benign payload in the login form parameters (such as a parameter containing <script>alert(1)</script>) and observe if it is reflected unchanged in the response
    Affected if Input is reflected back in the HTML response without sanitization or encoding

The environment is affected if any Forcepoint Cloud Security Gateway, Web Security, or Email Security Cloud installation has a version released before 2023-03-29 and the login portal is accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2023-03-29 or later
Fixed in 2023-03-29
Interim mitigation

Apply Forcepoint vendor patch released on or after 03/29/2023 to address input validation in login_form.mhtml modules.

Recommended fix High confidence

Forcepoint Cloud Security Gateway version 2023-03-29 or later; Forcepoint Web Security version 2023-03-29 or later

  1. 1. Identify the currently deployed version of Forcepoint Cloud Security Gateway or Forcepoint Web Security
  2. 2. Verify the current version is before 2023-03-29 (vulnerable)
  3. 3. Upgrade to Forcepoint Cloud Security Gateway version 2023-03-29 or later, or Forcepoint Web Security version 2023-03-29 or later
  4. 4. Confirm the upgrade completed successfully
  5. 5. Verify the login_form.mhtml module is no longer vulnerable to reflected XSS attacks

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Cloud Security Gateway Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-26291 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data