CVE-2026-81096: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-rg68-wg77-c3wm
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CVSS 10.0
CWE-94
Published
Advisory Summary

CVE-2026-81096 is a CRITICAL (CVSS 10.0) security vulnerability vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting Software libraries in the Maven ecosystem. The weakness occurs when 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.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-81096 at a Glance

CVE Identifier CVE-2026-81096
GHSA Identifier GHSA-rg68-wg77-c3wm
Severity CRITICAL
CVSS v3.1 Base Score 10.0
CWE Classification CWE-94: Improper Control of Generation of Code ('Code Injection')
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 10.0

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:C/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 Changed (S:C)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-81096

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-2026-81096, 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-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 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

ToolUniverse ran caller-supplied Python inside a sandbox that could be escaped, on a server that required no authentication. The executor behind the python_code_executor tool, in python_executor_tool.py, inspected the submitted source for a denied list of attribute names and calls but left the attribute-lookup builtins available and did not stop a dunder attribute reached through a string lookup or through a module already permitted, so a caller could walk from a literal's class to its base and enumerate subclasses to obtain a reference to the process and subprocess modules. A per-call argument also let the caller widen the import allow-list before the inspection ran. The HTTP and MCP servers in http_api_server.py and smcp_server.py bound to every interface with debugging enabled and no authentication, so any caller able to reach the port executed code as the server process. Version 1.3.0 adds bearer-token authentication, defaults the bind address to loopback, and hardens the attribute checks.

References

GitHub Advisory / Wiki ADVISORY
https://github.com/mims-harvard/ToolUniverse/security/advisories/GHSA-pxwq-22vf-87fm
NVD — CVE-2026-81096 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-81096
Software Source Repository REPOSITORY
https://github.com/mims-harvard/ToolUniverse/pull/251
Software Source Repository REPOSITORY
https://github.com/mims-harvard/ToolUniverse
www.vulncheck.com/advisories/tooluniv... WEB
https://www.vulncheck.com/advisories/tooluniverse-through-1.2.6-unauthenticated-remote-code-execution-via-python-code-executor-sandbox-escape

Frequently Asked Questions

What is CVE-2026-81096?
CVE-2026-81096 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-94: Improper Control of Generation of Code ('Code Injection').
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-81096?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-81096?
CVE-2026-81096 has a CVSS v3.1 base score of 10.0 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.
What CWE is associated with CVE-2026-81096?
CVE-2026-81096 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 Maven dependencies for CVE-2026-81096?
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-rg68-wg77-c3wm",
  "modified" : "2026-08-27T18:32:25Z",
  "published" : "2026-08-27T18:32:25Z",
  "aliases" : [ "CVE-2026-81096" ],
  "details" : "ToolUniverse ran caller-supplied Python inside a sandbox that could be escaped, on a server that required no authentication. The executor behind the python_code_executor tool, in python_executor_tool.py, inspected the submitted source for a denied list of attribute names and calls but left the attribute-lookup builtins available and did not stop a dunder attribute reached through a string lookup or through a module already permitted, so a caller could walk from a literal's class to its base and enumerate subclasses to obtain a reference to the process and subprocess modules. A per-call argument also let the caller widen the import allow-list before the inspection ran. The HTTP and MCP servers in http_api_server.py and smcp_server.py bound to every interface with debugging enabled and no authentication, so any caller able to reach the port executed code as the server process. Version 1.3.0 adds bearer-token authentication, defaults the bind address to loopback, and hardens the attribute checks.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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/mims-harvard/ToolUniverse/security/advisories/GHSA-pxwq-22vf-87fm"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-81096"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mims-harvard/ToolUniverse/pull/251"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mims-harvard/ToolUniverse"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/tooluniverse-through-1.2.6-unauthenticated-remote-code-execution-via-python-code-executor-sandbox-escape"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-94" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-27T17:20:51Z"
  }
}