dbcve.org
NetApplication · Golang

CVE-2026-42506

MEDIUM · 6.1 CVSS v3.1 Published 2026-05-22
Fix available
A fix is available. Upgrade to 0.55.0 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
Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.

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 · moderate confidence

A vulnerability exists where parsing arbitrary HTML and rendering it produces an unexpected HTML tree structure. This discrepancy between how HTML is parsed versus how it's rendered can bypass sanitization filters that attempt to clean input before rendering, leading to stored or reflected XSS.

MitigationImplement defense-in-depth by using mature sanitization libraries (e.g., DOMPurify, sanitize-html) configured with strict ALLOW lists, and ensure sanitization occurs AFTER DOM parsing rather than on raw string input.

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
NetApplication
Affected:< 0.55.0

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. Check installed golang.org/x/net version
    Run 'go list -m golang.org/x/net' in your project directory, or inspect your go.mod file for the 'golang.org/x/net' dependency version
    Affected if The version listed is below 0.55.0 (e.g., 0.54.0, 0.50.0, etc.)
  2. Identify HTML parsing usage
    Search your codebase for imports of 'golang.org/x/net/html' or 'golang.org/x/net/html/charset' packages, and identify functions that parse HTML input such as html.Parse, ParseFragment, or similar
    Affected if Your code imports and uses the golang.org/x/net HTML parser to process user-supplied or untrusted HTML content
  3. Confirm sanitization is in place
    Search for HTML sanitization logic that uses the golang.org/x/net/html package, such as sanitizer implementations or the parse tree construction that could be bypassed
    Affected if You rely on golang.org/x/net HTML parsing to sanitize HTML input and the parsing logic may fail to properly handle certain HTML constructs
  4. Check for untrusted HTML input
    Audit your application to determine if it accepts HTML content from external sources (user input, webhooks, API payloads, file uploads) and passes it through the golang.org/x/net HTML parser
    Affected if Your application processes untrusted HTML through the affected parser without additional upstream validation

You are affected if your project uses golang.org/x/net version below 0.55.0 and processes untrusted HTML input through the golang.org/x/net HTML parser that could be bypassed by specially crafted HTML constructs.

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 0.55.0 or later
Fixed in 0.55.0
Interim mitigation

Implement defense-in-depth by using mature sanitization libraries (e.g., DOMPurify, sanitize-html) configured with strict ALLOW lists, and ensure sanitization occurs AFTER DOM parsing rather than on raw string input.

Recommended fix Moderate confidence

golang.org/x/net v0.55.0 or later

  1. Locate the go.mod file in your project that references golang.org/x/net
  2. Update the golang.org/x/net dependency to version 0.55.0 or later by running: go get golang.org/x/[email protected]
  3. Run go mod tidy to clean up dependencies
  4. Rebuild your application and run tests to verify the upgrade does not break existing functionality

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

Fix this in Net Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

Scan for this in your stack

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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-2026-42506 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