CVE-2008-2316

Integer overflow in hashlib module

• CVSS 7.5
• CWE-189: Numeric Errors
• Numeric Errors
• Local

Integer overflow in _hashopenssl.c in the hashlib module in Python 2.5.2 and earlier might allow context-dependent attackers to defeat cryptographic digests, related to "partial hashlib hashing of data exceeding 4GB."

CVE

CVE-2008-2316

CWE

CWE-189: Numeric Errors

CVSS base score

7.5

Published

2008-08-01

OWASP

A08 Software and Data Integrity Failures

Orthogonal defect classification

Function

Code defect classification

Incorrect Functionality

Category

Numeric Errors

Subcategory

Integer Overflows

Accessibility scope

Local

Impact

Denial of Service (DoS)

Fixed by upgrading

Yes

Solution

Upgrade to Python 2.5.3 or higher.

import hashlib

class Hash:
    def __init__(self):
        self.hasher = hashlib.sha256()
        self.total_length = 0

    def update(self, data):
        self.hasher.update(data)
        self.total_length += len(data)

    def digest(self):
        return self.hasher.digest()

hash = Hash()
hash.update(b"A" * (2**31))
print(hash.digest())

import hashlib

class Hash:
    def __init__(self):
        self.hasher = hashlib.sha256()
        self.total_length = 0

    def update(self, data):
        data_length = len(data)
        if self.total_length + data_length > 2**63 - 1:
            raise ValueError("Data length exceeds the maximum allowed limit.")
        self.hasher.update(data)
        self.total_length += data_length

    def digest(self):
        return self.hasher.digest()

hash = Hash()
hash.update(b"some data")
print(hash.digest())

@misc{vaitp:cve20082316,
  title        = {{Integer overflow in hashlib module}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2008},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2008-2316},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2008-2316/}}
}