CVE-2026-34481

MEDIUM EPSS 42.1%
Published Apr 10, 20262mo ago · Modified Jun 17, 20262w ago
6.3 CVSS 4.0
Medium
Find Similar
Published Apr 10, 2026 2mo ago
Last Modified Jun 17, 2026 2w ago

Description

Apache Log4j's JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values (NaN, Infinity, or -Infinity), which are prohibited by RFC 8259. This may cause downstream log processing systems to reject or fail to index affected records. An attacker can exploit this issue only if both of the following conditions are met: * The application uses JsonTemplateLayout. * The application logs a MapMessage containing an attacker-controlled floating-point value. Users are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue.

CVSS Details

Base Score
6.3
Exploitability
—
Impact
—
Vector string
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/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
Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
42.1% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-116

Affected Products 7

VendorProductVersionRange
apachelog4j*≥2.14.0  –  <2.25.4
apachelog4j3.0.0any
apachelog4j3.0.0any
apachelog4j3.0.0any
apachelog4j3.0.0any
apachelog4j3.0.0any
apachelog4j3.0.0any

References 6

  • openwall.com http://www.openwall.com/lists/oss-security/2026/04/10/10
    Mailing ListThird Party Advisory
  • github.com https://github.com/apache/logging-log4j2/pull/4080
    Issue Tracking
  • lists.apache.org https://lists.apache.org/thread/n34zdv00gbkdbzt2rx9rf5mqz6lhopcv
    Mailing ListVendor Advisory
  • logging.apache.org https://logging.apache.org/cyclonedx/vdr.xml
    Product
  • logging.apache.org https://logging.apache.org/log4j/2.x/manual/json-template-layout.html
    Technical Description
  • logging.apache.org https://logging.apache.org/security.html#CVE-2026-34481
    Vendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.