CVE-2026-59809: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-27jw-6xjf-hgxj
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CVSS 4.9
CWE-201
Published
Advisory Summary

CVE-2026-59809 is a MODERATE (CVSS 4.9) security vulnerability vulnerability (CWE-201: Insertion of Sensitive Information Into Sent Data) affecting Software libraries in the Maven ecosystem. The weakness occurs when the code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-59809 at a Glance

CVE Identifier CVE-2026-59809
GHSA Identifier GHSA-27jw-6xjf-hgxj
Severity MODERATE
CVSS v3.1 Base Score 4.9
CWE Classification CWE-201: Insertion of Sensitive Information Into Sent Data
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 4.9

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

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

How to Fix CVE-2026-59809

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

Verify Direct and Transitive Dependencies

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

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-59809, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-201: Insertion of Sensitive Information Into Sent Data, where the code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor. In Software, 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

SiYuan before v3.8.0 interpolates secret placeholders into the destination URL parameter of the http_request MCP tool, allowing attackers to exfiltrate stored secrets. An MCP client can craft a request with an attacker-controlled URL containing secret placeholders to send plaintext secret values to any public host without confirmation.

References

GitHub Advisory / Wiki ADVISORY
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-853m-gvvm-6rvx
NVD — CVE-2026-59809 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59809
www.vulncheck.com/advisories/siyuan-b... WEB
https://www.vulncheck.com/advisories/siyuan-before-secret-exfiltration-via-http-request-url

Frequently Asked Questions

What is CVE-2026-59809?
CVE-2026-59809 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-201: Insertion of Sensitive Information Into Sent Data.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-59809?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-59809?
CVE-2026-59809 has a CVSS v3.1 base score of 4.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-59809?
CVE-2026-59809 is classified under CWE-201: Insertion of Sensitive Information Into Sent Data (The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.).
How can I check Maven dependencies for CVE-2026-59809?
Run the dependency tree command: 'mvn dependency:tree'. 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-27jw-6xjf-hgxj",
  "modified" : "2026-08-22T15:31:02Z",
  "published" : "2026-08-22T15:31:02Z",
  "aliases" : [ "CVE-2026-59809" ],
  "details" : "SiYuan before v3.8.0 interpolates secret placeholders into the destination URL parameter of the http_request MCP tool, allowing attackers to exfiltrate stored secrets. An MCP client can craft a request with an attacker-controlled URL containing secret placeholders to send plaintext secret values to any public host without confirmation.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-853m-gvvm-6rvx"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-59809"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/siyuan-before-secret-exfiltration-via-http-request-url"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-201" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-22T13:16:39Z"
  }
}