CVE-2026-47734 Dulwich has unbounded memory allocation in receive-pack from crafted thin packs

Dulwich is a pure-Python implementation of the Git file formats and protocols. Starting in version 0.1.0 and prior to version 1.2.5, a client with push access could push a tiny crafted thin pack 174 bytes whose delta header declares a huge destsize. When dulwich ingested it via addthinpack /...

CVE-2026-47734

Dulwich prior to 1.2.5 is vulnerable to an unbounded memory allocation in receive-pack when processing a crafted thin pack. A tiny push (~174 bytes) can declare a huge dest_size in the delta header, causing add_thin_pack / apply_delta to allocate hundreds of MB regardless of actual data. Impacted...

Memory Allocation with Excessive Size Value

Overview Affected versions of this package are vulnerable to Memory Allocation with Excessive Size Value through the ReceivePackHandler via addthinpack/applydelta flows when handling crafted thin packs with attacker-controlled delta headers. An attacker can cause excessive memory allocation by...

Dulwich has unbounded memory allocation in receive-pack from crafted thin packs

Impact An uncontrolled-resource-consumption memory exhaustion denial-of-service vulnerability CWE-400 / CWE-789. A client with push access could push a tiny crafted thin pack 174 bytes whose delta header declares a huge destsize. When dulwich ingested it via addthinpack / applydelta, it would...