CVE-2026-67276: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-j9wg-77fw-f22f
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CVSS 8.1
CWE-347
Published
Advisory Summary

CVE-2026-67276 is a CRITICAL (CVSS 8.1) security vulnerability vulnerability (CWE-347: Improper Verification of Cryptographic Signature) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product does not verify, or incorrectly verifies, the cryptographic signature for data.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-67276 at a Glance

CVE Identifier CVE-2026-67276
GHSA Identifier GHSA-j9wg-77fw-f22f
Severity CRITICAL
CVSS v3.1 Base Score 8.1
CWE Classification CWE-347: Improper Verification of Cryptographic Signature
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 8.1

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:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
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-2026-67276

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-2026-67276, 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-347: Improper Verification of Cryptographic Signature, where the product does not verify, or incorrectly verifies, the cryptographic signature for data. 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

RouterOS does not compare the complete RSA public key when matching an SSH authentication request to an authorized user key, checking the key type and modulus but omitting the exponent. Because signature verification uses the client-supplied key, an attacker knowing an authorized RSA modulus can supply a key with exponent one, forge a valid signature, and open an SSH command channel as the target user without the private key.This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)

References

npratley.net/reversing-mikrotiks... WEB
https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain
mikrotik.com/supportsec/septembe... WEB
https://mikrotik.com/supportsec/september-2026-vulnerability
NVD — CVE-2026-67276 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-67276
cert.pl/en/posts/2026/09/mi... WEB
https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve
cert.pl/en/posts/2026/09/vu... WEB
https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited
forum.mikrotik.com/t/6-49-21-long-term... WEB
https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802
forum.mikrotik.com/t/7-23-4-long-term-... WEB
https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801
forum.mikrotik.com/t/7-24-2-stable-is-... WEB
https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800

Frequently Asked Questions

What is CVE-2026-67276?
CVE-2026-67276 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-347: Improper Verification of Cryptographic Signature.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-67276?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-67276?
CVE-2026-67276 has a CVSS v3.1 base score of 8.1 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-67276?
CVE-2026-67276 is classified under CWE-347: Improper Verification of Cryptographic Signature (The product does not verify, or incorrectly verifies, the cryptographic signature for data.).
How can I check Maven dependencies for CVE-2026-67276?
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-j9wg-77fw-f22f",
  "modified" : "2026-09-25T15:31:25Z",
  "published" : "2026-09-05T21:31:19Z",
  "aliases" : [ "CVE-2026-67276" ],
  "details" : "RouterOS does not compare the complete RSA public key when matching an SSH authentication request to an authorized user key, checking the key type and modulus but omitting the exponent. Because signature verification uses the client-supplied key, an attacker knowing an authorized RSA modulus can supply a key with exponent one, forge a valid signature, and open an SSH command channel as the target user without the private key.This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/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" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-67276"
  }, {
    "type" : "WEB",
    "url" : "https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve"
  }, {
    "type" : "WEB",
    "url" : "https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited"
  }, {
    "type" : "WEB",
    "url" : "https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802"
  }, {
    "type" : "WEB",
    "url" : "https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801"
  }, {
    "type" : "WEB",
    "url" : "https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800"
  }, {
    "type" : "WEB",
    "url" : "https://mikrotik.com/supportsec/september-2026-vulnerability"
  }, {
    "type" : "WEB",
    "url" : "https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-347" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-05T20:17:17Z"
  }
}