Bug 2567440 (CVE-2026-102664)

Summary: CVE-2026-102664 proxysql: proxysql: Information disclosure via unverified compressed payload length
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in ProxySQL. When processing compressed client traffic, the proxy fails to verify that the actual decompressed data length matches the client-supplied payload size. An authenticated client can exploit this vulnerability by overstating the payload length, causing the proxy to read and forward uninitialized heap memory to the backend database. This issue primarily leads to information disclosure of sensitive data—such as credentials, session state, and previous query results—and can also trigger a denial of service (DoS) through excessive memory allocation.
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Description OSIDB Bzimport 2026-11-05 21:57:56 UTC 
ProxySQL is a proxy for MySQL and its forks, as well as PostgreSQL. Prior to 3.0.10, 3.1.10, and 4.0.10, decompress_mysql_payload() in lib/mysql_data_stream.cpp accepts a zlib stream when uncompress() returns Z_OK without checking that the actual output length equals the attacker-controlled payload_length. An authenticated MySQL client that negotiates compression can overstate payload_length, causing buffer2array() to parse the uninitialized tail of a heap buffer as MySQL packet headers and forward stale data to the backend. Backend error responses can disclose prior SQL queries, result data, credentials, or session state, and malformed lengths can also cause excessive allocations. This issue is fixed in versions 3.0.10, 3.1.10, and 4.0.10.