CVE-2026-55859Network attack vector

Data corruption via mid-session charset confusion

Published Aug 28, 2026 · Updated Aug 28, 2026

Improper output encoding in MariaDB Connector/R2DBC before 1.4.1 allows remote attackers to corrupt data through a mid-session charset change. The OK-packet session-state tracker accepts a non-UTF-8 character_set_client value while the driver keeps encoding and decoding every character as UTF-8. Reachability requires a hostile or man-in-the-middle server, or server-side state such as a routine, trigger, or configuration; the confirmed result is silent corruption, while SQL injection also requires affected byte-wise quoting or escaping.

CVSS severity5.9
Medium
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper output encoding in MariaDB Connector/R2DBC before 1.4.1 allows remote attackers to corrupt data through a mid-session charset change. The OK-packet session-state tracker accepts a non-UTF-8 character_set_client value while the driver keeps encoding and decoding every character as UTF-8. Reachability requires a hostile or man-in-the-middle server, or server-side state such as a routine, trigger, or configuration; the confirmed result is silent corruption, while SQL injection also requires affected byte-wise quoting or escaping.

The record

CVE
CVE-2026-55859
Published
Aug 28, 2026
Updated
Aug 28, 2026
Vendor
MariaDB
Product
MariaDB Connector/R2DBC
Classifications
CWE-116, CWE-838, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MariaDB · MariaDB Connector/R2DBCversion=< 1.4.1

Published CVSS scores

5.9GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-116Improper Encoding or Escaping of Output
CWE-838Inappropriate Encoding for Output Context
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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