CVE-2026-1225: Logback core Logback Allows An Attacker To Vulnerability

LOW
Advisory Identifier: GHSA-qqpg-mvqg-649v
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CWE-20
Published
Advisory Summary

CVE-2026-1225 is a LOW logback allows an attacker to vulnerability (CWE-20: Improper Input Validation) affecting Logback core libraries in the Maven ecosystem. The issue involves logback allows an attacker to instantiate classes already present on the class path. Remediation is available by upgrading affected packages to version 1.5.25.

CVE-2026-1225 at a Glance

CVE Identifier CVE-2026-1225
GHSA Identifier GHSA-qqpg-mvqg-649v
Severity LOW
CVSS v3.1 Base Score N/A
CWE Classification CWE-20: Improper Input Validation
Affected Product Logback core
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-1225

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

ch.qos.logback:logback-core fixed: 1.5.25 
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-core</artifactId>
    <version>1.5.25</version>
</dependency>
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 -Dincludes=ch.qos.logback

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-1225, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=ch.qos.logback

Analyze the terminal output to locate any version of Logback core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.5.25), your application is affected.

Note: The mvn dependency:tree -Dincludes=ch.qos.logback 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-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In Logback core, 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

ACE vulnerability in configuration file processing by QOS.CH logback-core up to and including version 1.5.24 in Java applications, allows an attacker to instantiate classes already present on the class path by compromising an existing logback configuration file. The instantiation of a potentially malicious Java class requires that said class is present on the user's class-path. In addition, the attacker must have write access to a configuration file. However, after successful instantiation, the instance is very likely to be discarded with no further ado.

CVE-2026-1225 Affected Logback core Versions

1 component(s)
Fixed Versions:
1.5.25
Product / Package Ecosystem Affected Versions Fixed Version
ch.qos.logback:logback-core
maven/ch.qos.logback/logback-core
Maven
< 1.5.25
1.5.25

References

NVD — CVE-2026-1225 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-1225
Logback core Source Repository REPOSITORY
https://github.com/qos-ch/logback/issues/997
Security Fix Commit FIX COMMIT
https://github.com/qos-ch/logback/commit/1f97ae1844b1be8486e4e9cade98d7123d3eded5
Logback core Source Repository REPOSITORY
https://github.com/qos-ch/logback
logback.qos.ch/news.html WEB
https://logback.qos.ch/news.html#1.5.25

Frequently Asked Questions

What is CVE-2026-1225?
CVE-2026-1225 is a security vulnerability in Logback core involving Logback allows an attacker to instantiate classes already present on the class path under CWE-20: Improper Input Validation.
Which Logback core versions are affected?
Affected versions include releases prior to 1.5.25 across affected packages: ch.qos.logback:logback-core.
What version fixes CVE-2026-1225?
Upgrading to 1.5.25 (or the latest patched release for your respective branch) resolves the vulnerability.
Is logback-core affected?
Yes, ch.qos.logback:logback-core is affected in releases prior to 1.5.25. Upgrade your dependency to 1.5.25 or later.
What CWE is associated with CVE-2026-1225?
CVE-2026-1225 is classified under CWE-20: Improper Input Validation (The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.).
How can I check Maven dependencies for CVE-2026-1225?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=ch.qos.logback'. 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-qqpg-mvqg-649v",
  "modified" : "2026-01-22T18:06:44Z",
  "published" : "2026-01-22T12:31:22Z",
  "aliases" : [ "CVE-2026-1225" ],
  "summary" : "Logback allows an attacker to instantiate classes already present on the class path",
  "details" : "ACE vulnerability in configuration file processing  by QOS.CH logback-core up to and including version 1.5.24 in Java applications, allows an attacker to instantiate classes already present on the class path by compromising an existing logback configuration file.\n\nThe instantiation of a potentially malicious Java class requires that said class is present on the user's class-path. In addition, the attacker must  have write access to a configuration file. However, after successful instantiation, the instance is very likely to be discarded with no further ado.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "ch.qos.logback:logback-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.5.25"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-1225"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/qos-ch/logback/issues/997"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/qos-ch/logback/commit/1f97ae1844b1be8486e4e9cade98d7123d3eded5"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/qos-ch/logback"
  }, {
    "type" : "WEB",
    "url" : "https://logback.qos.ch/news.html#1.5.25"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-22T18:06:44Z",
    "nvd_published_at" : "2026-01-22T10:16:07Z"
  }
}