ProxySQL: Uninitialized heap read in MySQL compressed packet decompression via zlib path
Affects ProxySQL before 3.0.10, 3.1.0 to 3.1.9, and 4.0.0 to 4.0.9 where clients use MySQL compression, which is on by default. Fixed in 3.0.10, 3.1.10 and 4.0.10.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 3.0.10, 3.1.10, 4.0.10
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Client negotiates compression (CLIENT_COMPRESS flag), which is enabled by default The zlib decompression path is used
- Exploitation?/40Exploitation: unknown (data gap). No CISA SSVC exploitation rating yet
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity7.1/10CVSS 7.1
- No patch0/5No signal
What would change the score
- Would score about 65 if added to CISA KEV
- Would score about 60 if CISA's SSVC rates exploitation active
- Would score about 22 if CISA's SSVC rates it automatable
CVE-2026-102664 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.1 (high) and affects proxysql; fixed in 3.0.10, 3.1.10 and 4.0.10.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 15/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 3.0.10, 3.1.10, 4.0.10
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
ProxySQL, a proxy for MySQL, PostgreSQL and their forks, has an uninitialized heap read in its zlib-based decompression of MySQL compressed packets. An attacker who can reach the service over the network with a low-privilege authenticated MySQL client that negotiates compression can make ProxySQL forward stale memory from the backend, potentially exposing prior SQL queries, result data, credentials, or session state.
Read the original description
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.
What to do
Check whether your setup matches what the bug needs.
Client negotiates compression (CLIENT_COMPRESS flag), which is enabled by default The zlib decompression path is usedUpgrade to a fixed version: 3.0.10, 3.1.10, 4.0.10.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- sysown proxysql
fixed in 3.0.10; From 3.1.0 · fixed in 3.1.10; From 4.0.0 · fixed in 4.0.10
Evidence 6
- Advisory
- Repository
- Repository
- Repository
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-102664
Is CVE-2026-102664 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
ProxySQL can read uninitialized heap memory while decompressing MySQL compressed packets on the zlib path. That memory may hold SQL queries, result set data, credentials, or session state from other users' connections. The flaw can also allow denial of service through excessive allocations.Source: github.com
Which versions are affected by CVE-2026-102664?
proxysql: before 3.0.10; from 3.1.0 before 3.1.10; from 4.0.0 before 4.0.10.Source: cve.now feed data
Am I affected, and how do I check?
Versions before 3.0.10, from 3.1.0 before 3.1.10, and from 4.0.0 before 4.0.10 are in the affected range. The bug needs a client to negotiate compression (CLIENT_COMPRESS) and the zlib path to be used, and compression is enabled by default through mysql-have_compress=true, so check the ProxySQL version and that variable.Source: github.com
How do I fix CVE-2026-102664?
Upgrade to 3.0.10, 3.1.10, or 4.0.10, depending on which release line is in use. Those releases are the listed fixed versions.Source: github.com