Is CVE-2026-40470 in the CISA KEV catalog?

No. CVE-2026-40470 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-40470?

CVE-2026-40470 has a CVSS v3 base score of 9.9 (CRITICAL).

What is the EPSS score for CVE-2026-40470?

CVE-2026-40470 has an EPSS score of 0.31% (22th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-40470

CRITICAL

9.9

CVSS v3

NVD

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.

CWE-79Cross-Site Scripting (XSS)

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityLow

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

Exploit Intelligence

0.31%probability of exploitation in 30 days

22ndpercentile

Low risk: more likely to be exploited than 22% of all known CVEs.

References

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

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-24.