{"id":"GHSA-5rqc-86vf-g8r2","summary":"org.mariadb:r2dbc-mariadb has Inappropriate Encoding for Output Context and Improper Encoding or Escaping of Output","details":"### Summary\n\nThe connector encodes and decodes all character data assuming the connection character set is UTF-8. A server can change character_set_client mid-session to a non-UTF-8 charset, after which the driver and server interpret the same bytes under different encodings, causing silent data corruption and a client/server charset-confusion mismatch.\n\n### Details\n\nThe driver encodes and decodes all character data on the assumption that the connection character set is UTF-8. The server can, however, announce a change of character_set_client mid-session through the OK-packet session-state-tracking mechanism, for example via a SET NAMES … run by a stored routine or trigger, by server configuration, or by a hostile server.\n\nIf the new charset is not UTF-8, the driver continues to read and write UTF-8 while the server interprets the same bytes under a different encoding. The result is silent data corruption and a client/server charset-confusion mismatch. Charset confusion of this kind is also the primitive that can defeat byte-wise quoting/escaping when client and server disagree on a multi-byte encoding.\n\n### Am I affected?\n\nYou are affected if you use mariadb Connector/R2DBC (org.mariadb:r2dbc-mariadb) below 1.4.1 and a connection can be steered, by a hostile or man-in-the-middle server, or by server-side state such as a stored routine, trigger, or configuration — to switch character_set_client to a non-UTF-8 value mid-session.\n\n### Impact\n\nSilent data corruption and a client/server encoding mismatch once the connection's charset diverges from UTF-8. Because the mismatch undermines the assumption that quoting/escaping operates on UTF-8 bytes, it belongs to the charset-confusion class that can lead to SQL injection.\n\n### Patches\n\nFixed in 1.4.1. Once the connection is fully initialized, any subsequent charset change to a value that is not utf8 / utf8mb3 / utf8mb4 is rejected: the driver raises R2dbcNonTransientResourceException (SQLState 08000) and closes the connection rather than continuing to exchange data under a mismatched encoding. Upgrade to 1.4.1 or later.\n\n### Workarounds\n\nThere is no reliable application-level workaround; upgrade to 1.4.1 or later.\n\n### Credit\n\nReported by Yalguun Tumenkhuu ([@fg0x0](https://github.com/fg0x0/)).","aliases":["CVE-2026-55859"],"modified":"2026-08-28T23:10:37.561415Z","published":"2026-08-28T22:49:03Z","database_specific":{"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-08-28T22:49:03Z","nvd_published_at":null,"cwe_ids":["CWE-116","CWE-838"]},"references":[{"type":"WEB","url":"https://github.com/mariadb-corporation/mariadb-connector-r2dbc/security/advisories/GHSA-5rqc-86vf-g8r2"},{"type":"WEB","url":"https://github.com/mariadb-corporation/mariadb-connector-r2dbc/commit/38bad9afebc6c581a853656a42f9ebf403b1b1b7"},{"type":"PACKAGE","url":"https://github.com/mariadb-corporation/mariadb-connector-r2dbc"},{"type":"WEB","url":"https://github.com/mariadb-corporation/mariadb-connector-r2dbc/releases/tag/1.4.1"},{"type":"WEB","url":"https://jira.mariadb.org/browse/R2DBC-124"}],"affected":[{"package":{"name":"org.mariadb:r2dbc-mariadb","ecosystem":"Maven","purl":"pkg:maven/org.mariadb/r2dbc-mariadb"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.4.1"}]}],"versions":["0.8.1-alpha1","0.8.2-alpha2","0.8.3-beta1","0.8.4-rc","1.0.0","1.0.1","1.0.2","1.0.3","1.1.0-beta","1.1.1-rc","1.1.2","1.1.3","1.1.4","1.2.0","1.2.1","1.2.2","1.2.3","1.3.0","1.3.1","1.4.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-5rqc-86vf-g8r2/GHSA-5rqc-86vf-g8r2.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"}]}