CVE-2026-44593Public exploitNetwork attack vector

Unauthenticated file write via legacy route traversal

Published May 28, 2026 · Updated May 28, 2026

Path traversal in esm.sh before 137_3 allows remote attackers to write attacker-controlled data to arbitrary server paths. The legacy router concatenates unsanitized request-path components into a buildStorage.Put key, letting filesystem normalization resolve relative segments outside storage. Network access to a legacy route is sufficient; writes inherit the server process's permissions, and code execution requires overwriting an executed binary or script.

CVSS severity8.7
High
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in esm.sh before 137_3 allows remote attackers to write attacker-controlled data to arbitrary server paths. The legacy router concatenates unsanitized request-path components into a buildStorage.Put key, letting filesystem normalization resolve relative segments outside storage. Network access to a legacy route is sufficient; writes inherit the server process's permissions, and code execution requires overwriting an executed binary or script.

The record

CVE
CVE-2026-44593
Published
May 28, 2026
Updated
May 28, 2026
Vendor
esm-dev
Product
esm.sh
Classifications
CWE-22, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 28, 2026CVE publishedPublication date reported by the CVE source.
  2. May 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=<= 137

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

esm-dev · esm.shversion=<= 137

Published CVSS scores

8.7GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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