python before versions 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1 and 3.7.0 is vulnerable to catastrophic backtracking in the difflib.IS_LINE_JUNK method. An attacker could use this flaw to cause denial of service.

{
                    "product": "python",
                    "vendor": "[UNKNOWN]",
                    "versions": [
                        {
                            "status": "affected",
                            "version": "python 2.7.15"
                        },
                        {
                            "status": "affected",
                            "version": "python 3.4.9"
                        },
                        {
                            "status": "affected",
                            "version": "python 3.5.6"
                        },
                        {
                            "status": "affected",
                            "version": "python 3.7.0"
                        }
                    ]
                }