Changelog 2026

- Fixed heap-buffer-overflow in `CompressionCodecT64` and process abort in `CompressionCodecMultiple` when decompressing malformed compressed data. Both issues were found by new libFuzzer targets. The codecs now throw an exception instead of crashing. [#99680](https://github.com/ClickHouse/ClickHouse/pull/99680) ([Rahul](https://github.com/motsc)).
- Delay processing until server has finished loading all the tables. [#99700](https://github.com/ClickHouse/ClickHouse/pull/99700) ([Seva Potapov](https://github.com/seva-potapov)).
- Fix MySQL dictionary source bypassing `RemoteHostFilter` for inline DDL params. [#99720](https://github.com/ClickHouse/ClickHouse/pull/99720) ([Shaohua Wang](https://github.com/tiandiwonder)).
- Fix logical error when iterating over data lake tables in `system.tables`. [#99739](https://github.com/ClickHouse/ClickHouse/pull/99739) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Fixed analysis of predicates with the `IN` function by text index with the preprocessor. Fixed the collision of searched tokens in the text index, which could lead to incorrect results. [#99755](https://github.com/ClickHouse/ClickHouse/pull/99755) ([Anton Popov](https://github.com/CurtizJ)).
- Fix infinite loop when reading `Npy` format files with negative shape dimensions. [#99812](https://github.com/ClickHouse/ClickHouse/pull/99812) ([Desel72](https://github.com/Desel72)).
- Fix global-buffer-overflow in `CRC32` function on `FixedString` arguments when evaluated with zero rows during query plan header computation. [#99835](https://github.com/ClickHouse/ClickHouse/pull/99835) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fix crash (null pointer dereference) when executing `ALTER TABLE ... MODIFY COLUMN ... COMMENT` on Iceberg tables. [#99838](https://github.com/ClickHouse/ClickHouse/pull/99838) ([Desel72](https://github.com/Desel72)).
- Fix `aggregate_functions_null_for_empty` setting to work with aggregate functions returning non-Nullable types such as `Array` or `Map` (e.g., `groupArray`, `sumMap`). [#99839](https://github.com/ClickHouse/ClickHouse/pull/99839) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fix LOGICAL\_ERROR exception in `midpoint` function when called with mixed signed/unsigned integer types. [#99867](https://github.com/ClickHouse/ClickHouse/pull/99867) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fix "Block structure mismatch" exception in queries with HAVING clause where the filter expression contains both an aggregate wrapped in a NULL-producing function and `materialize(0)`. [#99915](https://github.com/ClickHouse/ClickHouse/pull/99915) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fix assertion failure in `sipHash128Keyed` (and similar keyed hash functions) when the data argument is a Map with array keys or other nested array types. [#99921](https://github.com/ClickHouse/ClickHouse/pull/99921) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fix `LOGICAL_ERROR` exception "Not-ready Set" in `IN` function during query plan optimization with `convertAnyJoinToSemiOrAntiJoin`. [#99939](https://github.com/ClickHouse/ClickHouse/pull/99939) ([Alexey Milovidov](https://github.com/alexey-milovidov)).