Vulnerability · Published Apr 23, 2026 · Assigned by redhat-cnalr
CVE-2026-40470Hackage package and doc upload stored XSS vulnerability
Critical 9.9
In plain English
A critical-severity cross-site scripting in hackage-server. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| hackage-server | 0.1 – before 0.6 |
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L