Answer in brief
CVE-2026-55859 records a Medium severity (CVSS 5.9) vulnerability in MariaDB Connector/R2DBC: Inappropriate Encoding for Output Context and Improper Encoding or Escaping of Output in org.mariadb:r2dbc-mariadb. The current sources do not mark it as known exploited. The current feed maps mariadb-corporation/mariadb-connector-r2dbc (generic), org.mariadb/r2dbc-mariadb (generic), org.mariadb:r2dbc-mariadb (maven). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.9. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps mariadb-corporation/mariadb-connector-r2dbc (generic), org.mariadb/r2dbc-mariadb (generic), org.mariadb:r2dbc-mariadb (maven). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| mariadb-corporation/mariadb-connector-r2dbcgeneric | < 1.4.1 | Not reported |
| org.mariadb/r2dbc-mariadbgeneric | < 1.4.1 | Not reported |
| org.mariadb:r2dbc-mariadbmaven | <1.4.1 | 1.4.1 |
Published upstream
Aug 28, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 28, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 28, 2026
MariaDB Connector/R2DBC is a non-blocking MariaDB and MySQL client implemented in Java. Prior to 1.4.1, org.mariadb:r2dbc-mariadb encodes and decodes all character data under the assumption that the connection character set is UTF-8. A server can announce a mid-session change to character_set_client through the OK-packet session-state-tracking mechanism, including through SET NAMES executed by a stored routine or trigger, server configuration, or a hostile or man-in-the-middle server. If the new character set is not UTF-8, the driver continues to exchange UTF-8 while the server interprets the same bytes under a different encoding, causing silent data corruption and a client/server charset-confusion mismatch that can defeat byte-wise quoting or escaping. The fix accepts only utf8, utf8mb3, or utf8mb4 after initialization; any other value raises R2dbcNonTransientResourceException with SQLState 08000 and closes the connection. This issue is fixed in version 1.4.1.
Quoted source text, attributed separately from HOL analysis.