Hackage package and doc upload stored XSS vulnerability
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- High · High · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-79.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | hackage-server | 0.1 to before 0.6 | 0.6 | Patch available | CNA |
- hackage-server Vendor— Affected 0.1 to before 0.6 Fixed in 0.6 Patch available CNA
Remediation
- Fix · CNA hackage-server Fixed in 0.6
Timeline
- 2026-10-02 Threatist record created from CVE-2026-40470
- 2026-10-03 Alias added: GHSA-hxp4-rf8g-9mwq
References
Sources
- CVE-2026-40470 · CVE Program
- CVE-2026-40470 · NVD
- FIRST EPSS
- GHSA-hxp4-rf8g-9mwq · GitHub Advisory Database · CC BY 4.0
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