CVE-2026-40472
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 · uneditedIn hackage-server, user-controlled metadata from .cabal files are rendered into HTML href attributes without proper sanitization, enabling stored Cross-Site Scripting (XSS) attacks.
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 confidenceIn hackage-server, metadata extracted from .cabal files (such as package descriptions, maintainer info, or custom fields) is rendered directly into HTML href attributes without sanitization or encoding. Attackers can craft malicious .cabal files containing XSS payloads in metadata fields that persist in the package database and execute when other users view the package page.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L
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 checksWork through these to decide whether this CVE applies to you.
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Confirm hackage-server is installedCheck for hackage-server process or examine package manager listings for haskell/hackage-server packagesAffected if hackage-server is running as the package repository server
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Identify hackage-server versionRun 'hackage-server --version' or check the installed package version via your package manager (cabal list, apt show hackage-server, etc.)Affected if version is within the affected range (if known) or unpatched for this XSS vulnerability
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Verify web interface is enabledCheck server configuration files (typically in /etc/hackage or ~/.hackage) for web interface settings, or confirm port 8080/80 is accessible for the UIAffected if the web UI is enabled and accessible to users viewing package pages
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Confirm .cabal file upload capability is activeInspect hackage-server configuration for upload-related settings (enableUploads, allow uploads, etc.)Affected if users can upload or publish .cabal files to the server
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Inspect HTML rendering of package metadataExamine server source code or template files for href attribute rendering - look for where package metadata fields are inserted into HTML without escaping (search for 'href=' patterns in templates)Affected if metadata fields are rendered directly into href attributes without HTML entity encoding
If hackage-server is running with the web UI and package upload/viewing enabled, and metadata is rendered into href attributes without sanitization, the environment is vulnerable to XSS via malicious .cabal file metadata.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataImplement strict input validation and output encoding for all .cabal metadata before rendering into HTML href attributes; consider using a whitelist approach for allowed characters and applying context-aware HTML escaping.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-40472 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-40472 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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