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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-34478 Detail

Description

Apache Log4j Core's Rfc5424Layout https://logging.apache.org/log4j/2.x/manual/layouts.html#RFC5424Layout , in versions 2.21.0 through 2.25.3, is vulnerable to log injection via CRLF sequences due to undocumented renames of security-relevant configuration attributes. Two distinct issues affect users of stream-based syslog services who configure Rfc5424Layout directly: * The newLineEscape attribute was silently renamed, causing newline escaping to stop working for users of TCP framing (RFC 6587), exposing them to CRLF injection in log output. * The useTlsMessageFormat attribute was silently renamed, causing users of TLS framing (RFC 5425) to be silently downgraded to unframed TCP (RFC 6587), without newline escaping. Users of the SyslogAppender are not affected, as its configuration attributes were not modified. Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

Nist CVSS score does not match with CNA score
CNA:  Apache Software Foundation
CVSS-B 6.9 MEDIUM
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

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
http://www.openwall.com/lists/oss-security/2026/04/10/7 CVE
https://github.com/apache/logging-log4j2/pull/4074 Apache Software Foundation
https://lists.apache.org/thread/3k1clr2l6vkdnl4cbhjrnt1nyjvb5gwt Apache Software Foundation
https://logging.apache.org/cyclonedx/vdr.xml Apache Software Foundation
https://logging.apache.org/log4j/2.x/manual/layouts.html#RFC5424Layout Apache Software Foundation
https://logging.apache.org/security.html#CVE-2026-34478 Apache Software Foundation

Weakness Enumeration

CWE-ID CWE Name Source
CWE-117 Improper Output Neutralization for Logs Apache Software Foundation  
CWE-684 Incorrect Provision of Specified Functionality Apache Software Foundation  

Change History

2 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-34478
NVD Published Date:
04/10/2026
NVD Last Modified:
04/10/2026
Source:
Apache Software Foundation