CVE-2026-39087: Heckel.io/ntfy/v2 Ntfy.sh Allows A Remote Attacker Vulnerability

CRITICAL
Advisory Identifier: GHSA-pqhx-w72w-m393
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CVSS 9.8
CWE-94
Published
Advisory Summary

CVE-2026-39087 is a CRITICAL (CVSS 9.8) ntfy.sh allows a remote attacker vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting Heckel.io/ntfy/v2 libraries in the Go ecosystem. The issue involves ntfy.sh allows a remote attacker to execute arbitrary code via the parseactions function. Remediation is available by upgrading affected packages to version 2.22.0.

CVE-2026-39087 at a Glance

CVE Identifier CVE-2026-39087
GHSA Identifier GHSA-pqhx-w72w-m393
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-94: Improper Control of Generation of Code ('Code Injection')
Affected Product Heckel.io/ntfy/v2
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 9.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-39087

To remediate this vulnerability, upgrade all affected Heckel.io/ntfy/v2 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

heckel.io/ntfy/v2 fixed: 2.22.0 
Upgrade heckel.io/ntfy/v2 to 2.22.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for heckel.io/ntfy/v2

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-39087, inspect your project dependencies for Heckel.io/ntfy/v2:

inspect dependencies for heckel.io/ntfy/v2

Analyze the terminal output to locate any version of Heckel.io/ntfy/v2 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.22.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-94: Improper Control of Generation of Code ('Code Injection'), where the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. In Heckel.io/ntfy/v2, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

An issue in Ntfy ntfy.sh before v.2.22.0 allows a remote attacker to execute arbitrary code via the parseActions function.

CVE-2026-39087 Affected Heckel.io/ntfy/v2 Versions

1 component(s)
Fixed Versions:
2.22.0
Product / Package Ecosystem Affected Versions Fixed Version
heckel.io/ntfy/v2
golang/heckel.io/ntfy/v2
Go
< 2.22.0
2.22.0

References

NVD — CVE-2026-39087 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39087
Heckel.io/ntfy/v2 Source Repository REPOSITORY
https://gist.github.com/MightyNawaf/5d41d6e8ead16e217f86b016002ecae5
Heckel.io/ntfy/v2 Source Repository REPOSITORY
https://github.com/binwiederhier/ntfy
Heckel.io/ntfy/v2 Release RELEASE
https://github.com/binwiederhier/ntfy/releases/tag/v2.22.0
ntfy.com WEB
http://ntfy.com
ntfysh.com WEB
http://ntfysh.com

Frequently Asked Questions

What is CVE-2026-39087?
CVE-2026-39087 is a security vulnerability in Heckel.io/ntfy/v2 involving ntfy.sh allows a remote attacker to execute arbitrary code via the parseActions function under CWE-94: Improper Control of Generation of Code ('Code Injection').
Which Heckel.io/ntfy/v2 versions are affected?
Affected versions include releases prior to 2.22.0 across affected packages: heckel.io/ntfy/v2.
What version fixes CVE-2026-39087?
Upgrading to 2.22.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is heckel.io/ntfy/v2 affected?
Yes, heckel.io/ntfy/v2 is affected in releases prior to 2.22.0. Upgrade your dependency to 2.22.0 or later.
What is the CVSS score of CVE-2026-39087?
CVE-2026-39087 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-39087?
CVE-2026-39087 is classified under CWE-94: Improper Control of Generation of Code ('Code Injection') (The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.).
How can I check Go dependencies for CVE-2026-39087?
Run the dependency tree command: 'inspect dependencies for heckel.io/ntfy/v2'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-pqhx-w72w-m393",
  "modified" : "2026-05-08T16:32:47Z",
  "published" : "2026-04-23T18:33:03Z",
  "aliases" : [ "CVE-2026-39087" ],
  "summary" : "ntfy.sh allows a remote attacker to execute arbitrary code via the parseActions function",
  "details" : "An issue in Ntfy ntfy.sh before v.2.22.0 allows a remote attacker to execute arbitrary code via the parseActions function.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "heckel.io/ntfy/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.22.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-39087"
  }, {
    "type" : "WEB",
    "url" : "https://gist.github.com/MightyNawaf/5d41d6e8ead16e217f86b016002ecae5"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/binwiederhier/ntfy"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/binwiederhier/ntfy/releases/tag/v2.22.0"
  }, {
    "type" : "WEB",
    "url" : "http://ntfy.com"
  }, {
    "type" : "WEB",
    "url" : "http://ntfysh.com"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-94" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-08T16:32:46Z",
    "nvd_published_at" : "2026-04-23T16:16:25Z"
  }
}