Is CVE-2026-27730 in the CISA KEV catalog?

No. CVE-2026-27730 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-27730?

CVE-2026-27730 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2026-27730?

CVE-2026-27730 has an EPSS score of 0.34% (26th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-27730

HIGH

7.5

CVSS v3

NVD

Description

esm.sh is a no-build content delivery network (CDN) for web development. Versions up to and including 137 have an SSRF vulnerability (CWE-918) in esm.sh’s `/http(s)` fetch route. The service tries to block localhost/internal targets, but the validation is based on hostname string checks and can be bypassed using DNS alias domains. This allows an external requester to make the esm.sh server fetch internal localhost services. As of time of publication, no known patched versions exist.

CWE-918Server-Side Request Forgery (SSRF)

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

0.34%probability of exploitation in 30 days

26thpercentile

Low risk: more likely to be exploited than 26% of all known CVEs.

References

https://github.com/esm-dev/esm.sh/security/advisories/GHSA-p2v6-84h2-5x4r

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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 2026-02-27.