CVE-2026-34478

Published: Apr 10, 2026 Last Modified: Apr 13, 2026
ExploitDB:
Other exploit source:
Google Dorks:
MEDIUM 6,9
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: none
User Interaction: none
Confidentiality: N/A
Integrity: N/A
Availability: N/A

Description

AI Translation Available

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.

EPSS (Exploit Prediction Scoring System)

Trend Analysis

EPSS (Exploit Prediction Scoring System)

Prevede la probabilità di sfruttamento basata su intelligence sulle minacce e sulle caratteristiche della vulnerabilità.

EPSS Score
0,0015
Percentile
0,3th
Updated

EPSS Score Trend (Last 6 Days)

117

Improper Output Neutralization for Logs

Draft
Abstraction: Base Structure: Simple
Common Consequences
Security Scopes Affected:
Integrity Confidentiality Availability Non-Repudiation
Potential Impacts:
Modify Application Data Hide Activities Execute Unauthorized Code Or Commands
Applicable Platforms
All platforms may be affected
Likelihood of Exploit: Medium
View CWE Details
684

Incorrect Provision of Specified Functionality

Draft
Abstraction: Class Structure: Simple
Common Consequences
Security Scopes Affected:
Other
Potential Impacts:
Quality Degradation
Applicable Platforms
All platforms may be affected
View CWE Details
http://www.openwall.com/lists/oss-security/2026/04/10/7
http://www.openwall.com/lists/oss-security/2026/04/10/7
https://github.com/apache/logging-log4j2/pull/4074
https://github.com/apache/logging-log4j2/pull/4074
https://lists.apache.org/thread/3k1clr2l6vkdnl4cbhjrnt1nyjv…
https://lists.apache.org/thread/3k1clr2l6vkdnl4cbhjrnt1nyjvb5gwt
https://logging.apache.org/cyclonedx/vdr.xml
https://logging.apache.org/cyclonedx/vdr.xml
https://logging.apache.org/log4j/2.x/manual/layouts.html#RF…
https://logging.apache.org/log4j/2.x/manual/layouts.html#RFC5424Layout
https://logging.apache.org/security.html#CVE-2026-34478
https://logging.apache.org/security.html#CVE-2026-34478