CVE-2026-49844: Apache Log4j API: Improper encoding of non-finite floating-point values during MapMessage JSON serialization
(updated )
Improper encoding of non-finite floating-point values during MapMessage JSON serialization in Apache Log4j API produces output that is not valid JSON. This issue affects Apache Log4j API versions 2.13.1 through 2.25.4 and version 2.26.0.
The fix for CVE-2026-34481 did not cover all code paths: when a MapMessage contains a non-finite IEEE 754 value (NaN, Infinity, or -Infinity), MapMessage.asJson() emits the corresponding bare token. RFC 8259 does not permit these tokens, so a conformant parser rejects the resulting document.
The defect is reachable only when both of the following conditions hold:
References
- github.com/advisories/GHSA-qv9r-c865-cp47
- github.com/apache/logging-log4j2/commit/19edb23e162d6c728a8c2221a240037d389ed300
- github.com/apache/logging-log4j2/commit/feadf8eb0b4acb6ddfa4c0ab2bbc6d88b8e12d82
- github.com/apache/logging-log4j2/pull/4163
- github.com/apache/logging-log4j2/releases/tag/rel/2.25.5
- github.com/apache/logging-log4j2/releases/tag/rel/2.26.1
- logging.apache.org/cyclonedx/vdr.xml
- logging.apache.org/log4j/2.x/manual/json-template-layout.html
- logging.apache.org/security.html
- nvd.nist.gov/vuln/detail/CVE-2026-49844
Code Behaviors & Features
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