CVE-2026-34479 Vulnerability Analysis & Exploit Details

CVE-2026-34479
Vulnerability Scoring

7.5
/10
Very High Risk

Highly exploitable, CVE-2026-34479 poses a critical security risk that could lead to severe breaches.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Network
    Vulnerability is exploitable over a network without physical access.
  • Privileges Required: None
    No privileges are required for exploitation.
  • Scope: Unchanged
    Exploit remains within the originally vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2026-34479 Details

Status: Analyzed

Last updated: 🕕 06 May 2026, 18:21 UTC
Originally published on: 🕓 10 Apr 2026, 16:16 UTC

Time between publication and last update: 26 days

CVSS Release: version 3

CVSS3 Source

nvd@nist.gov

CVSS3 Type

Primary

CVSS3 Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVE-2026-34479 Vulnerability Summary

CVE-2026-34479: The Log4j1XmlLayout from the Apache Log4j 1-to-Log4j 2 bridge fails to escape characters forbidden by the XML 1.0 standard, producing malformed XML output. Conforming XML parsers are required to reject documents containing such characters with a fatal error, which may cause downstream log processing systems to drop or fail to index affected records. Two groups of users are affected: * Those using Log4j1XmlLayout directly in a Log4j Core 2 configuration file. * Those using the Log4j 1 configuration compatibility layer with org.apache.log4j.xml.XMLLayout specified as the layout class. Users are advised to upgrade to Apache Log4j 1-to-Log4j 2 bridge version 2.25.4, which corrects this issue. Note: The Apache Log4j 1-to-Log4j 2 bridge is deprecated and will not be present in Log4j 3. Users are encouraged to consult the Log4j 1 to Log4j 2 migration guide https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html , and specifically the section on eliminating reliance on the bridge.

Assessing the Risk of CVE-2026-34479

Access Complexity Graph

The exploitability of CVE-2026-34479 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2026-34479

With low attack complexity and no required privileges, CVE-2026-34479 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2026-34479, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2026-34479, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-34479 has no significant impact on data confidentiality.
  • Integrity: High
    CVE-2026-34479 could allow unauthorized modifications to data, potentially affecting system reliability and trust.
  • Availability: None
    CVE-2026-34479 does not impact system availability.

CVE-2026-34479 References

External References

CWE Common Weakness Enumeration

CWE-116

CAPEC Common Attack Pattern Enumeration and Classification

  • Cross Zone Scripting CAPEC-104 An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security.
  • User-Controlled Filename CAPEC-73 An attack of this type involves an adversary inserting malicious characters (such as a XSS redirection) into a filename, directly or indirectly that is then used by the target software to generate HTML text or other potentially executable content. Many websites rely on user-generated content and dynamically build resources like files, filenames, and URL links directly from user supplied data. In this attack pattern, the attacker uploads code that can execute in the client browser and/or redirect the client browser to a site that the attacker owns. All XSS attack payload variants can be used to pass and exploit these vulnerabilities.
  • Web Server Logs Tampering CAPEC-81 Web Logs Tampering attacks involve an attacker injecting, deleting or otherwise tampering with the contents of web logs typically for the purposes of masking other malicious behavior. Additionally, writing malicious data to log files may target jobs, filters, reports, and other agents that process the logs in an asynchronous attack pattern. This pattern of attack is similar to "Log Injection-Tampering-Forging" except that in this case, the attack is targeting the logs of the web server and not the application.
  • AJAX Footprinting CAPEC-85 This attack utilizes the frequent client-server roundtrips in Ajax conversation to scan a system. While Ajax does not open up new vulnerabilities per se, it does optimize them from an attacker point of view. A common first step for an attacker is to footprint the target environment to understand what attacks will work. Since footprinting relies on enumeration, the conversational pattern of rapid, multiple requests and responses that are typical in Ajax applications enable an attacker to look for many vulnerabilities, well-known ports, network locations and so on. The knowledge gained through Ajax fingerprinting can be used to support other attacks, such as XSS.

Vulnerable Configurations

  • cpe:2.3:a:apache:log4j:2.7:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.7:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.7:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.7:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.7:rc2:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.7:rc2:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.8:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.8:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.8.1:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.8.1:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.8.1:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.8.1:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.8.2:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.8.2:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.8.2:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.8.2:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.8:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.8:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.9.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.9.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.9.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.9.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.9.1:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.9.1:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.10.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.10.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.10.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.10.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.11.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.11.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.11.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.11.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.11.1:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.11.1:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.11.1:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.11.1:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.11.2:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.11.2:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.11.2:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.11.2:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.11.2:rc2:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.11.2:rc2:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.11.2:rc3:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.11.2:rc3:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.0:rc2:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.0:rc2:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.1:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.1:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.1:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.1:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.2:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.2:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.2:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.2:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.3:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.3:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.3:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.3:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.4:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.4:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.12.4:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.12.4:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.13.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.13.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.13.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.13.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.13.0:rc2:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.13.0:rc2:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.13.1:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.13.1:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.13.1:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.13.1:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.13.1:rc2:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.13.1:rc2:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.13.2:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.13.2:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.13.2:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.13.2:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.13.3:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.13.3:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.13.3:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.13.3:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.14.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.14.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.14.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.14.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.14.1:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.14.1:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.14.1:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.14.1:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.15.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.15.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.15.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.15.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.15.0:rc2:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.15.0:rc2:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.15.1:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.15.1:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.16.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.16.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.16.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.16.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.17.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.17.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.17.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.17.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.17.1:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.17.1:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.17.1:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.17.1:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.18.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.18.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.18.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.18.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.19.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.19.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.19.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.19.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.19.0:rc2:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.19.0:rc2:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.20.0:-:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.20.0:-:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.20.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.20.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.21.0:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.21.0:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.21.1:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.21.1:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.22.0:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.22.0:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.22.1:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.22.1:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.23.0:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.23.0:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.23.1:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.23.1:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.24.0:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.24.0:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.24.1:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.24.1:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.24.2:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.24.2:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.24.3:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.24.3:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.25.0:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.25.0:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.25.1:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.25.1:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.25.2:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.25.2:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:2.25.3:*:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:2.25.3:*:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:3.0.0:alpha1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:3.0.0:alpha1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc2:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc2:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:3.0.0:beta1:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:3.0.0:beta1:*:*:*:*:*:*
  • cpe:2.3:a:apache:log4j:3.0.0:beta2:*:*:*:*:*:*
    cpe:2.3:a:apache:log4j:3.0.0:beta2:*:*:*:*:*:*

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