Apache Cassandra Release Notes

Highlights from current and recent Apache Cassandra releases. For complete patch-level changes, see the upstream CHANGES.txt files linked at the bottom of each version stream.

5.0.x

Cassandra 5.0.9 (August 2026) - Current Release

Coordinator load-shedding returns OverloadedException without setting streamId, misrouting query responses (CASSANDRA-21508)
SAI (Storage-Attached Indexes) component checksum validation made segment-aware (CASSANDRA-21516)
Support Python 3.12 and 3.13 in cqlsh (CASSANDRA-20997)
Fix AssertionError in hasReplicaWithOngoingRepair when parallel_repair_count > 1 (CASSANDRA-21426)
putShortVolatile is not volatile in InMemoryTrie (CASSANDRA-21353)
Fix RequestFailureReason serializer (CASSANDRA-21437)
Remove golang dependency in gen-doc, replaced with a Python implementation (CASSANDRA-21432)
Use estimated compressed size for tables when checking free space for a compaction (CASSANDRA-21245)
Fix failing select on system_views.settings for non-string keys (CASSANDRA-21348)
Ensure SAI sends range tombstones to the coordinator for queries on static columns (CASSANDRA-21332)

Cassandra 5.0.8 (April 2026)

Backport Automated Repair Inside Cassandra for CEP-37 (CASSANDRA-21138)
Update cassandra-stress to support TLS 1.3 by default by auto-negotiation (CASSANDRA-21007)
Ensure schema created before 2.1 without tableId in folder name can be loaded in SnapshotLoader (CASSANDRA-21173)
Harden data resurrection startup check with atomic heartbeat file write with fallback (CASSANDRA-21290) (merged from the 4.1 branch)
Improved observability in AutoRepair to report both expected vs. actual repair bytes and expected vs. actual keyspaces (CASSANDRA-20581) (backported from 6.0)
Stop repair scheduler if two major versions are detected (CASSANDRA-20048) (backported from 6.0)
AutoRepair: Safeguard Full repair against disk protection (CASSANDRA-20045) (backported from 6.0)
Stop AutoRepair monitoring thread upon Cassandra shutdown (CASSANDRA-20623) (backported from 6.0)
Fix race condition in auto-repair scheduler (CASSANDRA-20265) (backported from 6.0)
Implement minimum repair task duration setting for auto-repair scheduler (CASSANDRA-20160) (backported from 6.0)
Implement preview_repaired auto-repair type (CASSANDRA-20046) (backported from 6.0)
Automated Repair Inside Cassandra for CEP-37 (CASSANDRA-19918) (backported from 6.0)

For previous 5.0.x patch release details, see the Apache Cassandra changelog.

Cassandra 5.0.0 (September 2024) - Major Release

Storage-Attached Indexes (SAI) (CEP-7) - Efficient secondary indexing (experimental in 4.0+, production-ready in 5.0)
Vector data type and search (CEP-30) - Approximate nearest neighbor searching via SAI
Unified Compaction Strategy (UCS) (CEP-26) - Adaptive compaction replacing multiple strategies
Trie memtables (CEP-19) - Trie-based in-memory data structures
Trie SSTables (CEP-25) - Trie-indexed SSTable format
Dynamic Data Masking (CEP-20) - Selective redaction of sensitive data at query time
Java 17 support - recommended for Cassandra 5.0
TTL and writetime on collections/UDTs - Extended metadata for complex types
CIDR-based authorizer (CEP-33) - Network-based access control
New math functions: abs, exp, log, log10, round

4.1.x

Cassandra 4.1.12 (August 2026) - Current 4.1 Release

Coordinator load-shedding returns OverloadedException without setting streamId, misrouting query responses (CASSANDRA-21508; introduced in 4.1.6, so 4.0.x is not affected)
Add Paxos v2 (a second lightweight-transaction protocol implementation) option and information in cassandra.yaml (CASSANDRA-21316)
Harden data resurrection startup check with atomic heartbeat file write with fallback (CASSANDRA-21290)
Bound declared value length against readable bytes in CBUtil (CASSANDRA-21521) (merged from 4.0)
Verify extension type before initializing reflectively-loaded classes (CASSANDRA-21525) (merged from 4.0)
Rename conflicting nodetool import --copy-data short option from -p to -cd (CASSANDRA-20214) (merged from 4.0)
Fix PasswordObfuscator failing to obfuscate certain passwords (CASSANDRA-21113) (merged from 4.0)
Fix negative memtable allocator ownership when an update is shadowed by an existing row deletion (CASSANDRA-21469) (merged from 4.0)
Consider first token of SSTable when calculating SSTable intersection in LeveledScanner (CASSANDRA-21369) (merged from 4.0)
Remove inFlightEcho entry on ECHO_REQ failure (CASSANDRA-21428) (merged from 4.0)
Validate snapshot names (CASSANDRA-21389) (merged from 4.0)
Fix BTree.FastBuilder.reset() failing to clear savedBuffer and savedNextKey, causing ClassCastException and SSTable header corruption during schema disagreement (CASSANDRA-21216, CASSANDRA-21260) (merged from 4.0)
Backport CASSANDRA-17810 fix and improve RTBoundValidator error messages (CASSANDRA-18282) (merged from 4.0)

Cassandra 4.1.11 (March 2026)

Disk usage guardrail cannot be disabled when failure threshold is reached (CASSANDRA-21057)
ReadCommandController should close fast to avoid deadlock when building secondary index (CASSANDRA-19564)
Redact security-sensitive information in system_views.settings (CASSANDRA-20856)
Rate limit password changes (CASSANDRA-21202)
Obsolete expired SSTables before compaction starts (CASSANDRA-19776)
Switch lz4-java to at.yawk.lz4 version due to CVE (CASSANDRA-21052)
Fix memory leak in BufferPoolAllocator when capacity needs to be extended (CASSANDRA-20753)
Add option to disable cqlsh history (CASSANDRA-21180)

Cassandra 4.1.0 (December 2022) - Major Release

Paxos v2 - Enhanced lightweight transaction protocol
Guardrails - Operational safety boundaries and limits
Partition denylist - Block access to problematic partitions
Top partition tracking - Per-table monitoring of hot partitions
Native transport rate limiting - Request throughput controls
Client-side password hashing - Enhanced authentication security
Pluggable memtables - Custom memtable implementations

For previous 4.1.x patch release details, see the Apache Cassandra changelog.

4.0.x

Cassandra 4.0.21 (August 2026) - Current 4.0 Release

Bound declared value length against readable bytes in CBUtil (CASSANDRA-21521)
Verify extension type before initializing reflectively-loaded classes (CASSANDRA-21525)
Rename conflicting nodetool import --copy-data short option from -p to -cd (CASSANDRA-20214)
Fix PasswordObfuscator failing to obfuscate certain passwords (CASSANDRA-21113)
Fix negative memtable allocator ownership when an update is shadowed by an existing row deletion (CASSANDRA-21469)
Consider first token of SSTable when calculating SSTable intersection in LeveledScanner (CASSANDRA-21369)
Remove inFlightEcho entry on ECHO_REQ failure (CASSANDRA-21428)
Validate snapshot names (CASSANDRA-21389)
Fix BTree.FastBuilder.reset() failing to clear savedBuffer and savedNextKey, causing ClassCastException and SSTable header corruption (CASSANDRA-21216, CASSANDRA-21260)
Backport CASSANDRA-17810 fix and improve RTBoundValidator error messages (CASSANDRA-18282)

Cassandra 4.0.20 (March 2026)

Rate limit password changes (CASSANDRA-21202)
Obsolete expired SSTables before compaction starts (CASSANDRA-19776)
Switch lz4-java to at.yawk.lz4 version due to CVE (CASSANDRA-21052)
Fix memory leak in BufferPoolAllocator when capacity needs to be extended (CASSANDRA-20753)
Fix cleanup of old incremental repair sessions on token range changes or table deletion (CASSANDRA-20877)
ArrayIndexOutOfBoundsException with repaired data tracking and counters (CASSANDRA-20871)
Add option to disable cqlsh history (CASSANDRA-21180)
Restrict BytesType compatibility to scalar types only (CASSANDRA-20982)

Cassandra 4.0.0 (July 2021) - Major Release

Virtual tables - System information via CQL queries
Audit logging - Comprehensive query audit trail
Full query logging - Capture all queries for replay
Incremental repair improvements - More efficient anti-entropy
Zero-copy streaming - Faster data transfer between nodes
Java 11 support - Modern JVM compatibility

For previous 4.0.x patch release details, see the Apache Cassandra changelog.

Version Compatibility

Version	Release Date	End of Support	Status
5.0.x	September 2024	Until 5.3.0 release	Current
4.1.x	December 2022	Until 5.2.0 release	Supported
4.0.x	July 2021	Until 5.1.0 release	Supported
3.11.x	June 2017	Unmaintained	Legacy

Upgrade Path

Any 4.x release (4.0.x or 4.1.x) may upgrade directly to 5.0.x as a rolling upgrade. Direct upgrades that skip a major version line are not supported: to upgrade from 3.11.x, first upgrade to a 4.x release, then to 5.0.x.