CVE-2026-27730: GO-2026-4554 - esm.sh has SSRF localhost/private-network bypass in `/http(s)` module route in github.com/esm-dev/esm.sh

CVE-2026-27730 · Severity: low · CVSS 3 · Published 2026-02-27

esm.sh has SSRF localhost/private-network bypass in `/http(s)` module route in github.com/esm-dev/esm.sh

Technologies: github.com/esm-dev/esm.sh (Go). Vendors: Go.

Quick answers

Is CVE-2026-27730 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-27730 being exploited in the wild.
How severe is CVE-2026-27730?
Low severity, with a CVSS score of 3, published 27 February 2026.
Which products and versions are affected?
github.com/esm-dev/esm.sh (Go) SEMVER:introduced=0,fixed=0.0.0-20250616164159-0593516c4cfa.
Is there a fix for CVE-2026-27730?
Yes. github.com/esm-dev/esm.sh (Go): upgrade to 0.0.0-20250616164159-0593516c4cfa or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-27730?
Check whether you run github.com/esm-dev/esm.sh (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/esm-dev/esm.sh (Go): upgrade to 0.0.0-20250616164159-0593516c4cfa or later
    go get github.com/esm-dev/esm.sh@v0.0.0-20250616164159-0593516c4cfa

Affected products

  • github.com/esm-dev/esm.sh (Go) SEMVER:introduced=0,fixed=0.0.0-20250616164159-0593516c4cfa

Identifiers

  • CVE-2026-27730
  • GHSA-p2v6-84h2-5x4r
  • GO-2026-4554

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