CVE-2020-7212

The _encode_invalid_chars function in util/url.py in the urllib3 library 1.25.2 through 1.25.7 for Python allows a denial of service (CPU consumption) because of an inefficient algorithm. The percent_encodings array contains all matches of percent encodings. It is not deduplicated. For a URL of length N, the size of percent_encodings may be up to O(N). The next step (normalize existing percent-encoded bytes) also takes up to O(N) for each step, so the total time is O(N^2). If percent_encodings were deduplicated, the time to compute _encode_invalid_chars would be O(kN), where k is at most 484 ((10+6*2)^2).

• CVE ID
• CVE-2020-7212

• Assigner
• cve@mitre.org

• Vulnerability Status
• Analyzed

• Published Version
• 2020-03-06T20:15:12

• Last Modified Date
• 2020-03-09T16:55:14

• Version
• 2.0

• Vector String
• AV:N/AC:L/Au:N/C:N/I:N/A:C

• Access Vector
• NETWORK

• Access Compatibility
• LOW

• Authentication
• NONE

• Confidentiality Impact
• NONE

• Integrity Impact
• NONE

• Availability Impact
• COMPLETE

• Base Score
• 7.8

• Severity
• HIGH

• Exploitability Score
• 10

• Impact Score
• 6.9

• Version
• 3.1

• Vector String
• CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

• Attack Vector
• NETWORK

• Attack Compatibility
• LOW

• Privileges Required
• NONE

• User Interaction
• NONE

• Scope
• UNCHANGED

• Confidentiality Impact
• NONE

• Availability Impact
• HIGH

• Base Score
• 7.5

• Base Severity
• HIGH

• Exploitability Score
• 3.9

• Impact Score
• 3.6