Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout (Apache Software Foundation Apache Log4j JSON Template Layout)

CVE-2026-34481

MEDIUM 6.3

At a glance

Source: NVD
EPSS: EPSS 0.69 % · percentile 53 (2026-10-31)
State: PUBLISHED
Published: 2026-04-10 15:43 UTC
Updated: 2026-07-11 04:55 UTC
Assigner: apache
NVD status: Modified

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Description

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, or logs an object directly (e.g., via Logger.info(Object), which wraps it in an ObjectMessage), where the message contains an attacker-controlled floating-point value. Users are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue. Note: The fix released in version 2.25.4 did not cover all affected code paths. CVE-2026-49844 was assigned to the remaining issue, which concerns the MapMessage.asJson() serialization in Apache Log4j API and is fixed in versions 2.25.5 and 2.26.1.

Weaknesses (CWE)

CWE-116 — Improper Encoding or Escaping of Output

References

Scores

Version	Score	Vector	Scored by
CVSS 4.0	MEDIUM 6.3	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	apache
CVSS 4.0	MEDIUM 6.3	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	NVD · security@apache.org (Secondary)
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N	NVD · nvd@nist.gov (Primary)

Advisories

GHSA-w35j-pv5h-q9q9 — Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout

European references

ENISA EUVD · EUVD-2026-21412
GCVE · GCVE-0-2026-34481

CERT-FR advisories

CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
CERTFR-2026-AVI-1336 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-1291 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-1256 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-1206 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-1165 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-1121 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-1094 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-1049 — Multiples vulnérabilités dans Oracle MySQL · cert.ssi.gouv.fr
CERTFR-2026-AVI-0958 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-0920 — Multiples vulnérabilités dans Oracle Weblogic · cert.ssi.gouv.fr

Affected configurations (NVD CPE)

cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:* ≥ 2.14.0 < 2.25.4
cpe:2.3:a:apache:log4j:3.0.0:alpha1:*:*:*:*:*:*
cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc1:*:*:*:*:*:*
cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc2:*:*:*:*:*:*
cpe:2.3:a:apache:log4j:3.0.0:beta1:*:*:*:*:*:*
cpe:2.3:a:apache:log4j:3.0.0:beta2:*:*:*:*:*:*
cpe:2.3:a:apache:log4j:3.0.0:beta3:*:*:*:*:*:*

Affected products

Product	Versions
Apache Software Foundation · Apache Log4j JSON Template Layout	affected 2.14.0 < 2.25.4 ; affected 3.0.0-alpha1 ≤ 3.0.0-beta3

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)	Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD

🟡 Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout (Apache Software Foundation Apache Log4j JSON Template Layout)