Medium severity · published Jun 16, 2025
CVE-2025-4565
Unbounded recursion in Python Protobuf
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
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
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 17% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PY
Python-Protobuf · protocolbuffers
before 4.25.8; before 5.29.5; before 6.31.1; before 4.25.8; before 5.29.5; before 6.31.1 · source: vendor
PR
Protobuf-python · Google
before 4.25.8; 5.26.0 before 5.29.5; 6.30.0 before 6.31.1 · source: NVD