CVE-2026-40470 — Hackage package and doc upload stored XSS vulnerability
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 wer…
Published: 2026-04-23 · CVSS: 9.9 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7