CVE-2026-40470

9.9 criticalEPSS 0.3%

Critical (9.9). EPSS 0.3% chance of exploitation in the next 30 days.

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.

Severity

CVSS 3.1

9.9 critical

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L

EPSS: 0.3% chance of exploitation in the next 30 days; higher than 23% of CVEs (scores of 2026-10-31)
CWE: CWE-79
Published: 2026-04-23
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

References

https://osv.dev/vulnerability/HSEC-2024-0004

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