CVE-2026-27730 Vulnerability Analysis & Exploit Details

CVE-2026-27730
Vulnerability Scoring

8.6
/10
Severe Risk

Cybersecurity professionals consider CVE-2026-27730 an immediate threat requiring urgent mitigation.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Network
    Vulnerability is exploitable over a network without physical access.
  • Privileges Required: None
    No privileges are required for exploitation.
  • Scope: Changed
    Successful exploitation can impact components beyond the vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2026-27730 Details

Status: Received on 25 Feb 2026, 16:23 UTC

Published on: 25 Feb 2026, 16:23 UTC

CVSS Release: version 3

CVSS3 Source

security-advisories@github.com

CVSS3 Type

Secondary

CVSS3 Vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

CVE-2026-27730 Vulnerability Summary

CVE-2026-27730: 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.

Assessing the Risk of CVE-2026-27730

Access Complexity Graph

The exploitability of CVE-2026-27730 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2026-27730

With low attack complexity and no required privileges, CVE-2026-27730 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2026-27730, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2026-27730, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: High
    Exploiting CVE-2026-27730 can result in unauthorized access to sensitive data, severely compromising data privacy.
  • Integrity: None
    CVE-2026-27730 poses no threat to data integrity.
  • Availability: None
    CVE-2026-27730 does not impact system availability.

CVE-2026-27730 References

External References

CWE Common Weakness Enumeration

CWE-918

CAPEC Common Attack Pattern Enumeration and Classification

  • Server Side Request Forgery CAPEC-664 An adversary exploits improper input validation by submitting maliciously crafted input to a target application running on a server, with the goal of forcing the server to make a request either to itself, to web services running in the server’s internal network, or to external third parties. If successful, the adversary’s request will be made with the server’s privilege level, bypassing its authentication controls. This ultimately allows the adversary to access sensitive data, execute commands on the server’s network, and make external requests with the stolen identity of the server. Server Side Request Forgery attacks differ from Cross Site Request Forgery attacks in that they target the server itself, whereas CSRF attacks exploit an insecure user authentication mechanism to perform unauthorized actions on the user's behalf.

Protect Your Infrastructure against CVE-2026-27730: Combat Critical CVE Threats

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