From dcb76d0c2175d9e9be6688c83d2b753a9a7c864d Mon Sep 17 00:00:00 2001 From: aviralgarg05 Date: Fri, 9 Jan 2026 20:59:10 +0530 Subject: [PATCH 3/3] Fix Any recursion depth bypass in Python json_format.ParseDict This fixes a security vulnerability where nested google.protobuf.Any messages could bypass the max_recursion_depth limit, potentially leading to denial of service via stack overflow. The root cause was that _ConvertAnyMessage() was calling itself recursively via methodcaller() for nested well-known types, bypassing the recursion depth tracking in ConvertMessage(). The fix routes well-known type parsing through ConvertMessage() to ensure proper recursion depth accounting for all message types including nested Any. Fixes #25070 --- python/google/protobuf/json_format.py | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py index 6c3b1cb8c..3dda09d61 100644 --- a/python/google/protobuf/json_format.py +++ b/python/google/protobuf/json_format.py @@ -456,6 +456,17 @@ class _Parser(object): Raises: ParseError: In case of convert problems. """ + # Increment recursion depth at message entry. The max_recursion_depth limit + # is exclusive: a depth value equal to max_recursion_depth will trigger an + # error. For example, with max_recursion_depth=5, nesting up to depth 4 is + # allowed, but attempting depth 5 raises ParseError. + self.recursion_depth += 1 + if self.recursion_depth > self.max_recursion_depth: + raise ParseError( + 'Message too deep. Max recursion depth is {0}'.format( + self.max_recursion_depth + ) + ) message_descriptor = message.DESCRIPTOR full_name = message_descriptor.full_name if _IsWrapperMessage(message_descriptor): @@ -595,8 +606,11 @@ class _Parser(object): if _IsWrapperMessage(message_descriptor): self._ConvertWrapperMessage(value['value'], sub_message) elif full_name in _WKTJSONMETHODS: - methodcaller( - _WKTJSONMETHODS[full_name][1], value['value'], sub_message)(self) + # For well-known types (including nested Any), use ConvertMessage + # to ensure recursion depth is properly tracked + self.ConvertMessage( + value['value'], sub_message, '{0}.value'.format(path) + ) else: del value['@type'] self._ConvertFieldValuePair(value, sub_message) -- 2.53.0