Apache Log4j API: Improper serialization of non-finite floating-point values in MapMessage.asJson()
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · None
- Fix status
- Partial Red Hat: 24 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Apache | Apache Log4j API | 2.13.1 to before 2.25.5; 2.26.0 to before 2.26.1; 3.0.0-alpha1 – 3.0.0-beta2 | 2.25.5, 2.26.1 | Patch available | CNA |
| — | org.apache.logging.log4j:log4j-api (Maven) | 2.13.1 to before 2.25.5 | 2.25.5 | Patch available | GHSA-qv9r-c865-cp47 |
| — | org.apache.logging.log4j:log4j-api (Maven) | 2.26.0 to before 2.26.1 | 2.26.1 | Patch available | GHSA-qv9r-c865-cp47 |
- Apache Log4j API VendorApache Affected 2.13.1 to before 2.25.5; 2.26.0 to before 2.26.1; 3.0.0-alpha1 – 3.0.0-beta2 Fixed in 2.25.5, 2.26.1 Patch available CNA
- org.apache.logging.log4j:log4j-api (Maven) Vendor— Affected 2.13.1 to before 2.25.5 Fixed in 2.25.5 Patch available GHSA-qv9r-c865-cp47
- org.apache.logging.log4j:log4j-api (Maven) Vendor— Affected 2.26.0 to before 2.26.1 Fixed in 2.26.1 Patch available GHSA-qv9r-c865-cp47
CPE configurations NVD · 7
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:* | 2.13.1 to before 2.25.5 | Vulnerable | Apache |
| cpe:2.3:a:apache:log4j:2.26.0:*:*:*:*:*:*:* | 2.26.0 | Vulnerable | Apache |
| cpe:2.3:a:apache:log4j:3.0.0:alpha1:*:*:*:*:*:* | 3.0.0 alpha1 | Vulnerable | Apache |
| cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc1:*:*:*:*:*:* | 3.0.0 alpha1_rc1 | Vulnerable | Apache |
| cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc2:*:*:*:*:*:* | 3.0.0 alpha1_rc2 | Vulnerable | Apache |
| cpe:2.3:a:apache:log4j:3.0.0:beta1:*:*:*:*:*:* | 3.0.0 beta1 | Vulnerable | Apache |
| cpe:2.3:a:apache:log4j:3.0.0:beta2:*:*:*:*:*:* | 3.0.0 beta2 | Vulnerable | Apache |
- cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:* Versions 2.13.1 to before 2.25.5 Vulnerable ·Apache
- cpe:2.3:a:apache:log4j:2.26.0:*:*:*:*:*:*:* Versions 2.26.0 Vulnerable ·Apache
- cpe:2.3:a:apache:log4j:3.0.0:alpha1:*:*:*:*:*:* Versions 3.0.0 alpha1 Vulnerable ·Apache
- cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc1:*:*:*:*:*:* Versions 3.0.0 alpha1_rc1 Vulnerable ·Apache
- cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc2:*:*:*:*:*:* Versions 3.0.0 alpha1_rc2 Vulnerable ·Apache
- cpe:2.3:a:apache:log4j:3.0.0:beta1:*:*:*:*:*:* Versions 3.0.0 beta1 Vulnerable ·Apache
- cpe:2.3:a:apache:log4j:3.0.0:beta2:*:*:*:*:*:* Versions 3.0.0 beta2 Vulnerable ·Apache
Remediation
- Fix · CNA Apache Log4j API (Apache Software Foundation) Fixed in 2.25.5, 2.26.1
- Fix · GHSA-qv9r-c865-cp47 org.apache.logging.log4j:log4j-api (Maven) Fixed in 2.25.5 Advisory →
- Fix · GHSA-qv9r-c865-cp47 org.apache.logging.log4j:log4j-api (Maven) Fixed in 2.26.1 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Cryostat 4 | Affected | No fix yet: Fix deferred |
| OpenShift Serverless | Affected | No fix yet: Fix deferred |
| Red Hat AI Inference Server | Affected | No fix yet: Fix deferred |
| Red Hat AMQ Broker 7 | Affected | No fix yet: Fix deferred |
| Red Hat AMQ Clients | Affected | No fix yet: Fix deferred |
| Red Hat Data Grid 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat Fuse 7 | Affected | — |
| Red Hat JBoss Enterprise Application Platform 7 | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Enterprise Application Platform 8 | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Enterprise Application Platform Expansion Pack | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Web Server 5 | Affected | No fix yet: Fix deferred |
| Red Hat Offline Knowledge Portal | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Dev Spaces | Affected | No fix yet: Fix deferred |
| Red Hat Single Sign-On 7 | Affected | No fix yet: Fix deferred |
| Red Hat build of Apache Camel - HawtIO 4 | Affected | No fix yet: Fix deferred |
| Red Hat build of Apache Camel 4 for Quarkus 3 | Affected | No fix yet |
| Red Hat build of Apache Camel for Spring Boot 4 | Affected | No fix yet: Fix deferred |
| Red Hat build of Apicurio Registry 3 | Affected | — |
| streams for Apache Kafka 2 | Affected | No fix yet: Fix deferred |
| streams for Apache Kafka 3 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-49844
- 2026-10-03 Alias added: GHSA-qv9r-c865-cp47
- 2026-10-21 EPSS moved to the below the 50th percentile
- 2026-10-30 Affected versions changed · Red Hat
References
Advisory 3
Other 6
- https://logging.apache.org/log4j/2.x/manual/json-template-layout.html#event-template-resolver-message
- https://github.com/apache/logging-log4j2/commit/19edb23e162d6c728a8c2221a240037d389ed300
- https://github.com/apache/logging-log4j2/commit/feadf8eb0b4acb6ddfa4c0ab2bbc6d88b8e12d82
- https://github.com/apache/logging-log4j2
- https://github.com/apache/logging-log4j2/releases/tag/rel/2.25.5
- https://github.com/apache/logging-log4j2/releases/tag/rel/2.26.1
More Apache Log4j vulnerabilities
- TI-2021-19919 Apache Log4j2 JNDI features do not protect against attacker controlled LDAP and other JNDI related endpoints KEVCVSS 3.1CRITICAL 10.0
- TI-2021-20393 Apache Log4j2 Thread Context Message Pattern and Context Lookup Pattern vulnerable to a denial of service attack KEVCVSS 3.1CRITICAL 9.0
- TI-2017-03645 Deserialization of untrusted data in Apache Log4j CVSS 3.1CRITICAL 9.8
- TI-2019-13113 Deserialization of untrusted data in Apache Log4j CVSS 3.1CRITICAL 9.8
- TI-2022-07428 SQL injection in JDBC Appender in Apache Log4j V1 CVSS 3.1CRITICAL 9.8
- TI-2022-07425 Deserialization of untrusted data in JMSSink in Apache Log4j 1.x CVSS 3.1HIGH 8.8
Sources
- CVE-2026-49844 · CVE Program
- CVE-2026-49844 · NVD
- FIRST EPSS
- GHSA-qv9r-c865-cp47 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-49844 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences