CVE-2026-81099: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-p943-9hp2-h27q
Share
CVSS 6.8
CWE-346
Published
Advisory Summary

CVE-2026-81099 is a HIGH (CVSS 6.8) security vulnerability vulnerability (CWE-346: Origin Validation Error) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product does not properly verify that the source of data or communication is valid.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-81099 at a Glance

CVE Identifier CVE-2026-81099
GHSA Identifier GHSA-p943-9hp2-h27q
Severity HIGH
CVSS v3.1 Base Score 6.8
CWE Classification CWE-346: Origin Validation Error
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 6.8

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

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

How to Fix CVE-2026-81099

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-2026-81099, 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-346: Origin Validation Error, where the product does not properly verify that the source of data or communication is valid. 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

tiger-slack started its MCP HTTP transport without enabling the host allow-list the underlying SDK provides. mcp/src/httpServer.ts called the shared httpServerFactory helper and never set the DNS-rebinding-protection option, so the transport accepted a request whatever host it named, and a page in a browser could point a name it controlled at the address the server was bound to and drive the locally reachable Slack MCP server through the visitor's browser. The fix passes the option explicitly alongside a dependency update; the update alone would not have closed it. The repository publishes no release that brackets the fix, so the affected boundary is the commit preceding it.

References

NVD — CVE-2026-81099 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-81099
Software Source Repository REPOSITORY
https://github.com/timescale/tiger-slack/pull/146
Software Source Repository REPOSITORY
https://github.com/timescale/tiger-slack
www.vulncheck.com/advisories/timescal... WEB
https://www.vulncheck.com/advisories/timescale-tiger-slack-dns-rebinding-via-disabled-host-header-allow-list

Frequently Asked Questions

What is CVE-2026-81099?
CVE-2026-81099 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-346: Origin Validation Error.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-81099?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-81099?
CVE-2026-81099 has a CVSS v3.1 base score of 6.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-81099?
CVE-2026-81099 is classified under CWE-346: Origin Validation Error (The product does not properly verify that the source of data or communication is valid.).
How can I check Maven dependencies for CVE-2026-81099?
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-p943-9hp2-h27q",
  "modified" : "2026-08-27T18:32:26Z",
  "published" : "2026-08-27T18:32:26Z",
  "aliases" : [ "CVE-2026-81099" ],
  "details" : "tiger-slack started its MCP HTTP transport without enabling the host allow-list the underlying SDK provides. mcp/src/httpServer.ts called the shared httpServerFactory helper and never set the DNS-rebinding-protection option, so the transport accepted a request whatever host it named, and a page in a browser could point a name it controlled at the address the server was bound to and drive the locally reachable Slack MCP server through the visitor's browser. The fix passes the option explicitly alongside a dependency update; the update alone would not have closed it. The repository publishes no release that brackets the fix, so the affected boundary is the commit preceding it.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/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" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-81099"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/timescale/tiger-slack/pull/146"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/timescale/tiger-slack"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/timescale-tiger-slack-dns-rebinding-via-disabled-host-header-allow-list"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-346" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-27T17:20:52Z"
  }
}