## Fixed in ClickHouse 21.10.2.15, 2021-10-18 {#fixed-in-clickhouse-release-21-10-2-215-2021-10-18}
### CVE-2021-43304 {#cve-2021-43304}
Heap buffer overflow in Clickhouse's LZ4 compression codec when parsing a malicious query. There is no verification that the copy operations in the LZ4::decompressImpl loop and especially the arbitrary copy operation wildCopy<copy_amount>(op, ip, copy_end), don’t exceed the destination buffer’s limits.
Credits: JFrog Security Research Team
### CVE-2021-43305 {#cve-2021-43305}
Heap buffer overflow in Clickhouse's LZ4 compression codec when parsing a malicious query. There is no verification that the copy operations in the LZ4::decompressImpl loop and especially the arbitrary copy operation wildCopy<copy_amount>(op, ip, copy_end), don’t exceed the destination buffer’s limits. This issue is very similar to CVE-2021-43304, but the vulnerable copy operation is in a different wildCopy call.
Credits: JFrog Security Research Team
### CVE-2021-42387 {#cve-2021-42387}
Heap out-of-bounds read in Clickhouse's LZ4 compression codec when parsing a malicious query. As part of the LZ4::decompressImpl() loop, a 16-bit unsigned user-supplied value ('offset') is read from the compressed data. The offset is later used in the length of a copy operation, without checking the upper bounds of the source of the copy operation.
Credits: JFrog Security Research Team
### CVE-2021-42388 {#cve-2021-42388}
Heap out-of-bounds read in Clickhouse's LZ4 compression codec when parsing a malicious query. As part of the LZ4::decompressImpl() loop, a 16-bit unsigned user-supplied value ('offset') is read from the compressed data. The offset is later used in the length of a copy operation, without checking the lower bounds of the source of the copy operation.
Credits: JFrog Security Research Team
### CVE-2021-42389 {#cve-2021-42389}
Divide-by-zero in Clickhouse's Delta compression codec when parsing a malicious query. The first byte of the compressed buffer is used in a modulo operation without being checked for 0.
Credits: JFrog Security Research Team
### CVE-2021-42390 {#cve-2021-42390}
Divide-by-zero in Clickhouse's DeltaDouble compression codec when parsing a malicious query. The first byte of the compressed buffer is used in a modulo operation without being checked for 0.
Credits: JFrog Security Research Team
### CVE-2021-42391 {#cve-2021-42391}
Divide-by-zero in Clickhouse's Gorilla compression codec when parsing a malicious query. The first byte of the compressed buffer is used in a modulo operation without being checked for 0.
Аn attacker that has write access to ZooKeeper and who can run a custom server available from the network where ClickHouse runs, can create a custom-built malicious server that will act as a ClickHouse replica and register it in ZooKeeper. When another replica will fetch data part from the malicious replica, it can force clickhouse-server to write to arbitrary path on filesystem.
“remote” table function allowed arbitrary symbols in “user”, “password” and “default_database” fields which led to Cross Protocol Request Forgery Attacks.
ClickHouse MySQL client had “LOAD DATA LOCAL INFILE” functionality enabled that allowed a malicious MySQL database read arbitrary files from the connected ClickHouse server.
