Summary
MariaDB Connector/J: Rogue server can drive large heap allocations from server-declared lengths in OK packets
MariaDB Connector/J sized heap allocations from lengths declared by the server
in OK packets before checking that those lengths fit in the packet. A rogue or
MitM server can make the client allocate megabytes from a packet of a few bytes.
Details
When CLIENT_SESSION_TRACK is negotiated (the default), an OK packet carries an
info field followed by session-state blocks, each tracked variable being sent as a
length-encoded name and value. OkPacket.parse() and parseWithInfo() allocatednew byte[len] for the info field, the variable name and the value with the
server-declared len, then copied the packet data into it. The copy failed with anArrayIndexOutOfBoundsException when the packet was shorter, but only after the
allocation had taken place.
A server-declared length of 8 MiB in an 18-byte packet was enough to trigger an
8 MiB allocation; the integer-range validation of length-encoded values does not
help, since such lengths are valid positive integers.
The fix validates every server-declared length against the remaining packet bytes
before any allocation (ReadableByteBuf.checkLength() and a boundedreadBytes(int)), and stops reading the session state at the first inconsistent
entry.
Credit
Reported by fg0x0
Impact
Availability only: a malicious or compromised server, or a MitM, can drive
attacker-controlled heap allocations on every OK packet, creating GC pressure up toOutOfMemoryError in the client application. Exploitation requires control of the
server side of the connection; no authentication bypass, confidentiality or
integrity impact.
CVE-2026-119276 has a CVSS score of 5.9 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.3.7, 3.4.5, 3.5.11); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
org.mariadb.jdbc:mariadb-java-client to 3.3.7 or later; org.mariadb.jdbc:mariadb-java-client to 3.4.5 or later; org.mariadb.jdbc:mariadb-java-client to 3.5.11 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-119276? CVE-2026-119276 is a medium-severity security vulnerability in org.mariadb.jdbc:mariadb-java-client (maven), affecting versions >= 3.0.0, < 3.3.7. It is fixed in 3.3.7, 3.4.5, 3.5.11.
- How severe is CVE-2026-119276? CVE-2026-119276 has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of org.mariadb.jdbc:mariadb-java-client are affected by CVE-2026-119276? org.mariadb.jdbc:mariadb-java-client (maven) versions >= 3.0.0, < 3.3.7 is affected.
- Is there a fix for CVE-2026-119276? Yes. CVE-2026-119276 is fixed in 3.3.7, 3.4.5, 3.5.11. Upgrade to this version or later.
- Is CVE-2026-119276 exploitable, and should I be worried? Whether CVE-2026-119276 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-119276 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-119276?
- Upgrade
org.mariadb.jdbc:mariadb-java-clientto 3.3.7 or later - Upgrade
org.mariadb.jdbc:mariadb-java-clientto 3.4.5 or later - Upgrade
org.mariadb.jdbc:mariadb-java-clientto 3.5.11 or later
- Upgrade