> CVE-2026-34480 [MEDIUM]

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PUBLISHED
2026-04-10 16:16
MODIFIED
2026-04-10 16:16
CVSS_SCORE V3
6.9
EPSS (Prob. Exploit)
1.06%
Top 35.1%
DATA SOURCES:
NVD đź”— 2026-04-10 CWE MITRE đź”— 2026-11-01 FIRST EPSS đź”— 2026-11-08 GITHUB đź”— 2026-10-28 OSV đź”— 2026-11-02 MSRC đź”— 2026-08-01

> DESCRIPTION

Apache Log4j Core's XmlLayout https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout , in versions up to and including 2.25.3, fails to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#charsets producing invalid XML output whenever a log message or MDC value contains such characters. The impact depends on the StAX implementation in use: * JRE built-in StAX: Forbidden characters are silently written to the output, producing malformed XML. Conforming parsers must reject such documents with a fatal error, which may cause downstream log-processing systems to drop the affected records. * Alternative StAX implementations (e.g., Woodstox https://github.com/FasterXML/woodstox , a transitive dependency of the Jackson XML Dataformat module): An exception is thrown during the logging call, and the log event is never delivered to its intended appender, only to Log4j's internal status logger. Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue by sanitizing forbidden characters before XML output.

> AFFECTED_PRODUCTS

ℹ️ Aucun produit affecté n'a encore été publié par NVD pour cette CVE.

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:4.0/AV:N/AC:L/AT:N/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

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:4.0/AV:N/AC:L/AT:N/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
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Network (N)
Exploit possible à distance via réseau (HTTP, API, etc.)
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
None (N)
Aucune authentification requise
UI (Interaction Utilisateur)
User Interaction
None (N)
Aucune interaction utilisateur nécessaire
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
None (N)
Aucune divulgation d'informations
I (Impact Intégrité)
Integrity Impact
None (N)
Aucune modification de données possible
A (Impact Disponibilité)
Availability Impact
None (N)
Aucune interruption de service

> RÉSUMÉ DES IMPACTS

Confidentialité
None
Aucune divulgation d'informations
Intégrité
None
Aucune modification de données possible
Disponibilité
None
Aucune interruption de service

> WEAKNESSES

CWE-116

> CWE DETAILED DESCRIPTIONS

CWE-116: Improper Encoding or Escaping of Output - The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.

> RED HAT SECURITY ADVISORIES

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Red Hat Security Advisory: Red Hat Build of Apache Camel 4.18.1.P1 for Spring Boot release.
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> GITHUB SECURITY ADVISORY

GHSA-3pxv-7cmr-fjr4 MODERATE

Apache Log4j Core: Silent log event loss in XmlLayout due to unescaped XML 1.0 forbidden characters

AFFECTED PACKAGES:
MAVEN / org.apache.logging.log4j:log4j-core
>= 3.0.0-alpha1, <= 3.0.0-beta3
MAVEN / org.apache.logging.log4j:log4j-core
>= 2.0-alpha1, < 2.25.4
Fixed in: 2.25.4

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

Apache Log4j Core: Silent log event loss in XmlLayout due to unescaped XML 1.0 forbidden characters

AFFECTED PACKAGES:
Unknown / Unknown
7 versions affected
ALIASES:
GHSA-3pxv-7cmr-fjr4

> HISTORIQUE DES MODIFICATIONS

Première apparition
10/04/2026 16:16
Source: NVD
đź“Š ENRICHISSEMENT 01/05/2026 06:01
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-116: Improper Encoding or Escaping of Output - The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done in...
Total des modifications: 1 Dernière mise à jour: 6 months ago

> REFERENCES

https://github.com/apache/logging-log4j2/pull/4077
https://lists.apache.org/thread/5x0hcnng0chhghp6jgjdp3qmbbhfjzhb
https://logging.apache.org/cyclonedx/vdr.xml
https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout
https://logging.apache.org/security.html#CVE-2026-34480
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