EUVD-2026-21412
GHSA-w35j-pv5h-q9q9
CVSS Vector
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
Lifecycle Timeline
4Description
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.
Analysis
Apache Log4j JsonTemplateLayout versions up to 2.25.3 generate invalid JSON when logging non-finite floating-point values (NaN, Infinity, -Infinity), violating RFC 8259 and causing downstream log processing systems to fail indexing or reject records. An unauthenticated remote attacker can trigger this by controlling floating-point values in MapMessages logged by vulnerable applications, resulting in data loss or processing failures in log aggregation pipelines. …
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