There is a LOW severity vulnerability affecting CPython, specifically the http.cookies standard library module.
When parsing cookies that contained backslashes for quoted characters in the cookie value, the parser would use an algorithm with quadratic complexity, resulting in excess CPU resources being used while parsing the value.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Python | Python | * | 3.8.20 (excluding) |
| Python | Python | 3.9.0 (including) | 3.9.20 (excluding) |
| Python | Python | 3.10.0 (including) | 3.10.15 (excluding) |
| Python | Python | 3.11.0 (including) | 3.11.10 (excluding) |
| Python | Python | 3.12.0 (including) | 3.12.6 (excluding) |
| Python | Python | 3.13.0-alpha0 (including) | 3.13.0-alpha0 (including) |
| Python | Python | 3.13.0-alpha1 (including) | 3.13.0-alpha1 (including) |
| Python | Python | 3.13.0-alpha2 (including) | 3.13.0-alpha2 (including) |
| Python | Python | 3.13.0-alpha3 (including) | 3.13.0-alpha3 (including) |
| Python | Python | 3.13.0-alpha4 (including) | 3.13.0-alpha4 (including) |
| Python | Python | 3.13.0-alpha5 (including) | 3.13.0-alpha5 (including) |
| Python | Python | 3.13.0-alpha6 (including) | 3.13.0-alpha6 (including) |
| Python | Python | 3.13.0-beta1 (including) | 3.13.0-beta1 (including) |
| Python | Python | 3.13.0-beta2 (including) | 3.13.0-beta2 (including) |
| Python | Python | 3.13.0-beta3 (including) | 3.13.0-beta3 (including) |
| Python | Python | 3.13.0-beta4 (including) | 3.13.0-beta4 (including) |
| Python | Python | 3.13.0-rc1 (including) | 3.13.0-rc1 (including) |
| Red Hat Enterprise Linux 9 | RedHat | python3.9-0:3.9.21-1.el9_5 | * |
| Red Hat Enterprise Linux 9 | RedHat | python3.12-0:3.12.5-2.el9_5.3 | * |
| Red Hat Enterprise Linux 9 | RedHat | python3.11-0:3.11.9-7.el9_5.3 | * |
| Red Hat Enterprise Linux 9 | RedHat | python3.9-0:3.9.21-1.el9_5 | * |
| Python2.7 | Ubuntu | esm-apps/focal | * |
| Python2.7 | Ubuntu | esm-apps/jammy | * |
| Python2.7 | Ubuntu | esm-infra-legacy/trusty | * |
| Python2.7 | Ubuntu | esm-infra/bionic | * |
| Python2.7 | Ubuntu | esm-infra/xenial | * |
| Python2.7 | Ubuntu | focal | * |
| Python2.7 | Ubuntu | jammy | * |
| Python2.7 | Ubuntu | trusty/esm | * |
| Python3.10 | Ubuntu | jammy | * |
| Python3.12 | Ubuntu | noble | * |
| Python3.12 | Ubuntu | upstream | * |
| Python3.13 | Ubuntu | upstream | * |
| Python3.4 | Ubuntu | trusty/esm | * |
| Python3.5 | Ubuntu | esm-infra-legacy/trusty | * |
| Python3.5 | Ubuntu | esm-infra/xenial | * |
| Python3.5 | Ubuntu | trusty/esm | * |
| Python3.8 | Ubuntu | esm-infra/focal | * |
| Python3.8 | Ubuntu | focal | * |
| Python3.9 | Ubuntu | focal | * |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.