CVE-2025-4565: Google Protobuf-Python

Medium severity, CVSS 5.3. EPSS: 0.3% chance of exploitation in the next 30 days.

Any project that uses Protobuf Pure-Python backend to parse untrusted Protocol Buffers data containing an arbitrary number of recursive groups, recursive messages or a series of SGROUP tags can be corrupted by exceeding the Python recursion limit. This can result in a Denial of service by crashing the application with a RecursionError. We recommend upgrading to version =>6.31.1 or beyond commit 17838beda2943d08b8a9d4df5b68f5f04f26d901

Affected products

• Google Protobuf-Python: before 4.25.8 (fixed in 4.25.8); from 5.26.0, before 5.29.5 (fixed in 5.29.5); from 6.30.0, before 6.31.1 (fixed in 6.31.1)

Published 2025-06-16. Last modified 2026-06-17.