What is CVE-2026-49844?

CVE-2026-49844 is a medium-severity security vulnerability in org.apache.logging.log4j:log4j-api (maven), affecting versions >= 2.13.1, < 2.25.5. It is fixed in 2.25.5, 2.26.1.

Which versions of org.apache.logging.log4j:log4j-api are affected by CVE-2026-49844?

org.apache.logging.log4j:log4j-api (maven) versions >= 2.13.1, < 2.25.5 is affected.

Is there a fix for CVE-2026-49844?

Yes. CVE-2026-49844 is fixed in 2.25.5, 2.26.1. Upgrade to this version or later.

Is CVE-2026-49844 exploitable, and should I be worried?

Whether CVE-2026-49844 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2026-49844 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

CVE-2026-49844 in org.apache.logging.log4j:log4j-api

Q: Which versions of org.apache.logging.log4j:log4j-api are affected by CVE-2026-49844?

org.apache.logging.log4j:log4j-api (maven) versions >= 2.13.1, < 2.25.5 is affected.

Q: Is there a fix for CVE-2026-49844?

Yes. CVE-2026-49844 is fixed in 2.25.5, 2.26.1. Upgrade to this version or later.

Q: Is CVE-2026-49844 exploitable, and should I be worried?

Whether CVE-2026-49844 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2026-49844 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2026-49844?

Upgrade: org.apache.logging.log4j:log4j-api to 2.25.5 or later, org.apache.logging.log4j:log4j-api to 2.26.1 or later.

Summary

Apache Log4j API: Improper encoding of non-finite floating-point values during MapMessage JSON serialization

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:

The application uses the message resolver https://logging.apache.org/log4j/2.x/manual/json-template-layout.html#event-template-resolver-message 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.

Impact

Affected versions

org.apache.logging.log4j:log4j-api (>= 2.13.1, < 2.25.5) org.apache.logging.log4j:log4j-api (>= 2.26.0, < 2.26.1)

Security releases

org.apache.logging.log4j:log4j-api → 2.25.5 (maven) org.apache.logging.log4j:log4j-api → 2.26.1 (maven)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade the following packages to resolve this vulnerability:

org.apache.logging.log4j:log4j-api to 2.25.5 or later; org.apache.logging.log4j:log4j-api to 2.26.1 or later

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2026-49844? CVE-2026-49844 is a medium-severity security vulnerability in org.apache.logging.log4j:log4j-api (maven), affecting versions >= 2.13.1, < 2.25.5. It is fixed in 2.25.5, 2.26.1.
Which versions of org.apache.logging.log4j:log4j-api are affected by CVE-2026-49844? org.apache.logging.log4j:log4j-api (maven) versions >= 2.13.1, < 2.25.5 is affected.
Is there a fix for CVE-2026-49844? Yes. CVE-2026-49844 is fixed in 2.25.5, 2.26.1. Upgrade to this version or later.
Is CVE-2026-49844 exploitable, and should I be worried? Whether CVE-2026-49844 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2026-49844 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2026-49844?
- Upgrade org.apache.logging.log4j:log4j-api to 2.25.5 or later
- Upgrade org.apache.logging.log4j:log4j-api to 2.26.1 or later