@logtape/syslog: syslog log injection via unescaped control characters and unvalidated SD-NAME keys

Summary

LogTape is an unobtrusive logging library. Prior to 1.3.11, 2.0.14, and 2.1.5, the @logtape/syslog package's escapeStructuredDataValue() function in packages/syslog/src/syslog.ts does not neutralize C0 control characters from U+0000 through U+001F in structured data values, and formatStructuredData() inserts property keys without validating the RFC 5424 SD-NAME grammar. When includeStructuredData is true, an attacker-controlled newline can terminate an RFC 6587 non-transparent TCP syslog frame and make following bytes appear as a forged RFC 5424 record, while a key containing a closing bracket or other forbidden character can terminate or corrupt the structured-data element. Applications that forward attacker-controlled property values or keys can therefore allow forged records with arbitrary hosts, applications, process identifiers, facilities, or severity levels, undermining downstream collector and SIEM integrity. This issue is fixed in versions 1.3.11, 2.0.14, and 2.1.5.

Timeline

1. Aug 26, 2026, 2:27 PM UTCCVE published
2. Aug 27, 2026, 1:55 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Aug 27, 2026, 2:33 PM UTCRecord last updated

Affected versions

• dahlia logtape

  fixed in 1.3.11; From 2.0.0 · fixed in 2.0.14; From 2.1.0 · fixed in 2.1.5

• @logtape/syslognpm

  From 2.1.0 · fixed in 2.1.5

• @logtape/syslognpm

  From 2.0.0 · fixed in 2.0.14

• @logtape/syslognpm

  fixed in 1.3.11

References 5