Medium [CVE-2026-49844] Malformed JSON output due to improper encoding of floating-point values
This medium-severity Red Hat Linux advisory covers CVE-2026-49844 affecting Cryostat 4, OpenShift Serverless, Red Hat AI Inference Server.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
Improper encoding of non-finite floating-point values during MapMessage JSON serialization in Apache Log4j API produces output that is not valid JSON. 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: * The application uses the message resolver of JsonTemplateLayout or any other layout that relies on MapMessage.asJson() or MapMessage.getFormattedMessage(new String[]{"JSON"}). * The application logs a MapMessage that contains an attacker-controlled floating-point value.
An attacker who can supply a non-finite value can cause the affected layout to emit malformed JSON, which may corrupt the enclosing log record or disrupt downstream log ingestion and parsing. Users are advised to upgrade to Apache Log4j API 2.25.5 or 2.26.1, both of which emit RFC 8259-compliant JSON for non-finite values.
This can corrupt log records or disrupt downstream log ingestion and parsing, potentially leading to a Denial of Service (DoS) or information integrity issues.
Is CVE-2026-49844 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-49844 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-49844?
Upgrade to a fixed release named by Red Hat:
- 2.25.5
- 2.26.1
Confirm against the vendor advisory before you patch.
- 2.13.1
- 2.25.4
- 2.26.0
Official advisory · high-confidence parse· fetched 1 month ago·verify at source
- 2.25.5
- 2.26.1
Official advisory · high-confidence parse· fetched 1 month ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official advisory · high-confidence parse· fetched 1 month ago·verify at source
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