Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-34481

Severity CVSS v4.0:
MEDIUM
Type:
Unavailable / Other
Publication date:
10/04/2026
Last modified:
24/04/2026

Description

Apache Log4j&amp;#39;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.<br /> <br /> An attacker can exploit this issue only if both of the following conditions are met:<br /> <br /> * The application uses JsonTemplateLayout.<br /> * The application logs a MapMessage containing an attacker-controlled floating-point value.<br /> <br /> <br /> Users are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue.

Impact

Vector 4.0
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 CVSS v4.0 Severity and Metrics:

Base Score: 6.30 MEDIUM
Vector: 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

Attack Vector (AV): Network
Attack Complexity (AC): High
Attack Requirements (AT): Present
Privileges Required (PR): None
User Interaction (UI): None
Confidentiality (VC): None
Integrity (VI): None
Availability (VA): None
Confidentiality (SC): None
Integrity (SI): Low
Availability (SA): None

Base Score 4.0
6.30
Severity 4.0
MEDIUM
Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N CVSS v3.1 Severity and Metrics:

Base Score: 7.50 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): High
Availability (A): None

Base Score 3.x
7.50
Severity 3.x
HIGH

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:* 2.14.0 (including) 2.25.4 (excluding)
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:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools