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CVE-2026-40472

9.9
Critical
EPSS 0.30%Apr 24, 2026

Stored XSS in hackage-server via unsanitized .cabal metadata in href attributes.

common questions

Is CVE-2026-40472 being exploited?

Not confirmed. CVE-2026-40472 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.30% probability of exploitation in the next 30 days.

How severe is CVE-2026-40472?

CVE-2026-40472 is rated Critical with a CVSS score of 9.9. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2026-40472?

Not known from our data. No patch reference has been recorded for CVE-2026-40472, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.

What does CVE-2026-40472 affect?

CVE-2026-40472 affects hackage-server. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

What should I do about CVE-2026-40472?

Sanitize metadata rendering; apply patch when released.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary
technical analysis
affected
hackage-server
impact

Stored XSS allows attacker to run scripts in victims' browsers via crafted metadata, enabling cookie/session theft or UI deception.

action required

Patch when possible

how to fix
Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.
references
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