Name | CVE-2020-7212 |

Description | 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). |

Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more) |

NVD severity | high |

The table below lists information on source packages.

Source Package | Release | Version | Status |
---|---|---|---|

python-urllib3 (PTS) | stretch | 1.19.1-1 | fixed |

buster | 1.24.1-1 | fixed | |

bullseye, sid | 1.25.9-1 | fixed |

The information below is based on the following data on fixed versions.

Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
---|---|---|---|---|---|---|

python-urllib3 | source | jessie | (not affected) | |||

python-urllib3 | source | stretch | (not affected) | |||

python-urllib3 | source | buster | (not affected) | |||

python-urllib3 | source | (unstable) | 1.25.8-1 |

[buster] - python-urllib3 <not-affected> (Vulnerable code introduced later)

[stretch] - python-urllib3 <not-affected> (Vulnerable code introduced later)

[jessie] - python-urllib3 <not-affected> (Vulnerable code introduced later)

https://github.com/urllib3/urllib3/pull/1787

Introduced by: https://github.com/urllib3/urllib3/commit/a74c9cfbaed9f811e7563cfc3dce894928e0221a (1.25.2)

Fixed by: https://github.com/urllib3/urllib3/commit/a2697e7c6b275f05879b60f593c5854a816489f0 (1.25.8)