CVE-2026-15747: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-6cg9-7rr8-cvj2
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CVSS 9.1
CWE-204
Published
Advisory Summary

CVE-2026-15747 is a CRITICAL (CVSS 9.1) security vulnerability vulnerability (CWE-204: Observable Response Discrepancy) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-15747 at a Glance

CVE Identifier CVE-2026-15747
GHSA Identifier GHSA-6cg9-7rr8-cvj2
Severity CRITICAL
CVSS v3.1 Base Score 9.1
CWE Classification CWE-204: Observable Response Discrepancy
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 9.1

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:N).

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 None (A:N)

How to Fix CVE-2026-15747

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-2026-15747, 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-204: Observable Response Discrepancy, where the product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere. 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

Mojolicious versions from 4.59 before 9.48 for Perl expose a stable representation of the session CSRF token to a BREACH compression oracle. _csrf_token generates and caches one token per session and returns the same value on every call, and _csrf_field places that value in a hidden `csrf_token` input. When a response carrying the token also echoes attacker-controlled input and is gzip-compressed, the chosen values and the resulting compressed lengths form a BREACH oracle. An attacker able to query it can recover the token and pass csrf_protect validation.

References

NVD — CVE-2026-15747 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-15747
Security Fix Commit FIX COMMIT
https://github.com/mojolicious/mojo/commit/01921fbbbbeca2d1397e082d4a647f9b84c24e27.patch
metacpan.org/release/sri/mojolic... WEB
https://metacpan.org/release/SRI/Mojolicious-9.48/changes
Software Security Information SECURITY
http://www.openwall.com/lists/oss-security/2026/07/14/16

Frequently Asked Questions

What is CVE-2026-15747?
CVE-2026-15747 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-204: Observable Response Discrepancy.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-15747?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-15747?
CVE-2026-15747 has a CVSS v3.1 base score of 9.1 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-15747?
CVE-2026-15747 is classified under CWE-204: Observable Response Discrepancy (The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere.).
How can I check Maven dependencies for CVE-2026-15747?
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-6cg9-7rr8-cvj2",
  "modified" : "2026-07-15T18:31:46Z",
  "published" : "2026-07-14T18:32:13Z",
  "aliases" : [ "CVE-2026-15747" ],
  "details" : "Mojolicious versions from 4.59 before 9.48 for Perl expose a stable representation of the session CSRF token to a BREACH compression oracle.\n\n_csrf_token generates and caches one token per session and returns the same value on every call, and _csrf_field places that value in a hidden `csrf_token` input. When a response carrying the token also echoes attacker-controlled input and is gzip-compressed, the chosen values and the resulting compressed lengths form a BREACH oracle.\n\nAn attacker able to query it can recover the token and pass csrf_protect validation.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-15747"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mojolicious/mojo/commit/01921fbbbbeca2d1397e082d4a647f9b84c24e27.patch"
  }, {
    "type" : "WEB",
    "url" : "https://metacpan.org/release/SRI/Mojolicious-9.48/changes"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2026/07/14/16"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-204" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-07-14T18:17:12Z"
  }
}