From b8ada4c2a07449fe8c4c4574292a501c1350c6e6 Mon Sep 17 00:00:00 2001 From: aviralgarg05 Date: Fri, 9 Jan 2026 20:59:10 +0530 Subject: [PATCH] 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 | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py index 2a6bba939..9ace6345e 100644 --- a/python/google/protobuf/json_format.py +++ b/python/google/protobuf/json_format.py @@ -521,6 +521,10 @@ 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( @@ -725,12 +729,11 @@ class _Parser(object): value['value'], sub_message, '{0}.value'.format(path) ) elif full_name in _WKTJSONMETHODS: - methodcaller( - _WKTJSONMETHODS[full_name][1], - value['value'], - sub_message, - '{0}.value'.format(path), - )(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, path) -- 2.52.0