CVE-2026-34480
highpriority · track · 30EPSS 0.010 · 64 %ileDEEUFRNLRUUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–high · 2.7–7.5
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (18)
Products and version ranges known to be affected.
- Maven org.apache.logging.log4j:log4j-core2.0-alpha1 → 2.25.4osvUSpkg:maven/org.apache.logging.log4j/log4j-core
- Maven org.apache.logging.log4j:log4j-core3.0.0-alpha1 → 3.0.0-beta3osvUSpkg:maven/org.apache.logging.log4j/log4j-core
advisories (10)
Vendor and ecosystem advisories describing this.
- NCSC-2026-0259Kwetsbaarheden verholpen in Oracle AnalyticsNL2026-07-22csaf · ncsc_nlNL
Oracle heeft meerdere kwetsbaarheden verholpen in Oracle BI Publisher (versies 8.2.0.0.0, 12.2.1.4.0 en 26.01.0.0.0) en Oracle Business Intelligence Enterprise Edition (versies 8.2.0.0.0 en 26.01.0.0.0).
- NCSC-2026-0378Kwetsbaarheden verholpen in Oracle Financial ServicesNL2026-09-16csaf · ncsc_nlNL
Oracle heeft 6 kwetsbaarheden verholpen in diverse Oracle Financial Services Applications-producten, waaronder Oracle Banking Branch, Oracle Banking Corporate Lending, Oracle Banking Origination, Oracle Banking Treasury Management en Oracle Banking Corporate Lending Process Management.
- WID-SEC-W-2026-1067Apache log4j: Mehrere Schwachstellen ermöglichen Manipulation von DateienDeutsch2026-04-12csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Apache log4j ausnutzen, um Dateien zu manipulieren.
- WID-SEC-W-2026-2260IBM Operational Decision Manager: Mehrere SchwachstellenDeutsch2026-07-08csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in IBM Operational Decision Manager ausnutzen, um beliebigen Programmcode auszuführen, um seine Privilegien zu erhöhen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren, und um Sicherheitsvorkehrungen zu umgehen.
- WID-SEC-W-2026-2437Oracle Communications: Mehrere SchwachstellenDeutsch2026-07-21csaf · cert_bundDE
Ein entfernter, anonymer oder authentisierter Angreifer kann mehrere Schwachstellen in Oracle Communications ausnutzen, um die Vertraulichkeit, Integrität und Verfügbarkeit zu gefährden.
- WID-SEC-W-2026-2444Oracle Fusion Middleware: Mehrere SchwachstellenDeutsch2026-07-21csaf · cert_bundDE
Ein entfernter, anonymer oder authentisierter Angreifer kann mehrere Schwachstellen in Oracle Fusion Middleware ausnutzen, um die Vertraulichkeit, Integrität und Verfügbarkeit zu gefährden.
- WID-SEC-W-2026-3398Oracle Financial Services Applications: Mehrere SchwachstellenDeutsch2026-09-15csaf · cert_bundDE
Ein entfernter, anonymer oder authentisierter Angreifer kann mehrere Schwachstellen in Oracle Financial Services Applications ausnutzen, um die Vertraulichkeit, Integrität und Verfügbarkeit zu gefährden.
- WID-SEC-W-2026-4084Oracle Siebel CRM: Mehrere SchwachstellenDeutsch2026-10-20csaf · cert_bundDE
Ein entfernter, anonymer oder authentisierter Angreifer kann mehrere Schwachstellen in Oracle Siebel CRM ausnutzen, um die Vertraulichkeit, Integrität und Verfügbarkeit zu gefährden.
- GHSA-3pxv-7cmr-fjr4Apache Log4j Core: Silent log event loss in XmlLayout due to unescaped XML 1.0 forbidden characters2026-04-10ghsa · osvUS
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.
- CERTFR-2026-AVI-1385Multiples vulnérabilités dans les produits VMwareFrançais2026-10-26vendor · certfrFR
also known as (4)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (19)
External citations — patches, advisories, analysis.
- http://www.openwall.com/lists/oss-security/2026/04/10/9cnnvd
- https://github.com/apache/logging-log4j2/pull/4077cnnvd
- https://lists.apache.org/thread/5x0hcnng0chhghp6jgjdp3qmbbhfjzhbcnnvd
- https://logging.apache.org/cyclonedx/vdr.xmlcnnvd
- https://logging.apache.org/log4j/2.x/download.htmlPatchcnnvd
- https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayoutcnnvd
- https://logging.apache.org/security.html#CVE-2026-34480cnnvd
- https://vigilance.fr/vulnerability/Apache-Log4j-multiple-vulnerabilities-dated-10-04-2026-50425cnnvd
Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.
Free scan