Search/CVE-2026-34478
CVE — High

CVE-2026-34478

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…

CVSS v3.1
7.5 HIGH
EPSS
0.97%
probability of exploitation in 30 days
CISA KEV
Not listed
no confirmed exploitation reported
News coverage
0
sources referencing this CVE
EPSS Trend
Aug 16, 2026Aug 26, 2026
0.14pp
0.83% → 0.97% over 2 tracked changes
CVSS v3.1 Detail
Attack VectorNETWORK
Attack ComplexityLOW
Privileges RequiredNONE
User InteractionNONE
ScopeUNCHANGED
ConfidentialityNONE
IntegrityHIGH
AvailabilityNONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Connections
2 relationships
Timeline
disclosure → media coverage
Apr 10, 2026
Disclosure — published as a CVE record. · last revised by NVD Apr 24, 2026