# CVE-2026-40470

> Vulnerability · severity: **CRITICAL** (CVSS 9.9).

## Description

A critical XSS vulnerability affected hackage-server and
hackage.haskell.org.  HTML and JavaScript files provided in source
packages or via the documentation upload facility were served
as-is on the main hackage.haskell.org domain.  As a consequence,
when a user with latent HTTP credentials browses to the package
pages or documentation uploaded by a malicious package maintainer,
their session can be hijacked to upload packages or
documentation, amend maintainers or other package metadata, or
perform any other action the user is authorised to do.

## Key facts

- **CVE ID:** CVE-2026-40470
- **Published:** 2026-04-23
- **CVSS severity:** CRITICAL
- **CVSS base score:** 9.9
- **CWE codes:** CWE-79

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40470

## Citation

> AI Analytics. CVE-2026-40470. Retrieved 2026-07-16 from https://api.ai-analytics.org/cve/CVE-2026-40470. Derived from NIST NVD. Licensed CC0.

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