A double free and use-after-free vulnerability in the RdbLoadDeletedNodes function of the RDB graph…

Why it is Amber

• CVSS 9.8 critical
• Remotely exploitable without logging in

References

• https://github.com/FalkorDB/FalkorDB/commit/523d98ac7ffe99f11a9c95c258025c235f0dff4c
• https://github.com/FalkorDB/FalkorDB/pull/1843
• https://github.com/FalkorDB/FalkorDB/releases/tag/v4.18.1

Original description

A double free and use-after-free vulnerability in the RdbLoadDeletedNodes function of the RDB graph decoders (src/serializers/decoders/*/decode_graph_entities.c) in FalkorDB before 4.18.1 allows a remote attacker who can issue Redis replication commands (for example, against an instance with no password configured) to cause a denial of service or execute arbitrary code in the redis-server process by supplying a crafted RDB stream whose deleted-nodes buffer length is not a multiple of sizeof(NodeID). The length check relies on ASSERT(), which is compiled out in release builds, so the function continues after freeing the buffer, reading it and freeing it a second time.