CVE-2026-558595.9MediumCWE-838

CVE-2026-55859: MariaDB Connector/R2DBC: Inappropriate Encoding for Output Context and Improper Encoding or Escaping of Output in org.mariadb:r2dbc-mariadb

mariadb-corporation · mariadb-connector-r2dbc

Affected: mariadb-corporation mariadb-connector-r2dbc · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.5%probability of exploitation in the next 30 days

42nd percentile

050100

Higher than 42% of scored CVEs

5.9MediumCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products2

From the CVE record. A product or version that is not listed is unknown, not unaffected.

mariadb-corporation · mariadb-connector-r2dbc< 1.4.1
org.mariadb · r2dbc-mariadb< 1.4.1

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Inappropriate Encoding for Output Context · Input Validation and Logic
Vendor: mariadb-corporation
Published: August 2026
Band: Unlikely (under 1%), August 2026
Bounty reports: 1 disclosed on HackerOne

Disclosed bug bounty reports about CVE-2026-55859

The reports on HackerOne that name this CVE, with HackerOne's own outcome. Titles and metadata only.

r2dbc-mariadb: server message accepted with no command in flight desynchronises the connection and serves one user's rows to anotherMariaDB · 2026 · medium severityValid

CoverageNo articles yet

No CyberSIXT article names CVE-2026-55859 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.