Pythons elementtree C accelerator failed to initialise Expats hash salt during initialization. This could make it easy to conduct denial of service attacks against Expat by constructing an XML document that would cause pathological hash collisions in Expats internal data structures, consuming large amounts CPU and RAM. The vulnerability exists in Python versions 3.7.0, 3.6.0 through 3.6.6, 3.5.0 through 3.5.6, 3.4.0 through 3.4.9, 2.7.0 through 2.7.15.
The product uses a Pseudo-Random Number Generator (PRNG) but does not correctly manage seeds.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Python | Python | 2.7.0 (including) | 2.7.15 (including) |
| Python | Python | 3.4.0 (including) | 3.4.9 (including) |
| Python | Python | 3.5.0 (including) | 3.5.6 (including) |
| Python | Python | 3.6.0 (including) | 3.6.6 (including) |
| Python | Python | 3.7.0 (including) | 3.7.0 (including) |
| Red Hat Ansible Tower 3.4 for RHEL 7 | RedHat | ansible-tower-34/ansible-tower-memcached:1.4.15-28 | * |
| Red Hat Ansible Tower 3.4 for RHEL 7 | RedHat | ansible-tower-35/ansible-tower-memcached:1.4.15-28 | * |
| Red Hat Ansible Tower 3.4 for RHEL 7 | RedHat | ansible-tower-37/ansible-tower-memcached-rhel7:1.4.15-28 | * |
| Red Hat Enterprise Linux 7 | RedHat | python-0:2.7.5-86.el7 | * |
| Red Hat Enterprise Linux 7.4 Advanced Update Support | RedHat | python-0:2.7.5-63.el7_4 | * |
| Red Hat Enterprise Linux 7.4 Telco Extended Update Support | RedHat | python-0:2.7.5-63.el7_4 | * |
| Red Hat Enterprise Linux 7.4 Update Services for SAP Solutions | RedHat | python-0:2.7.5-63.el7_4 | * |
| Red Hat Enterprise Linux 7.5 Extended Update Support | RedHat | python-0:2.7.5-74.el7_5 | * |
| Red Hat Enterprise Linux 7.6 Extended Update Support | RedHat | python-0:2.7.5-83.el7_6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 6 | RedHat | python27-python-0:2.7.16-4.el6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 6 | RedHat | python27-python-jinja2-0:2.6-12.el6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 6 | RedHat | rh-python36-python-0:3.6.9-2.el6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | RedHat | python27-python-0:2.7.16-4.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | RedHat | python27-python-jinja2-0:2.6-15.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | RedHat | rh-python36-python-0:3.6.9-2.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.4 EUS | RedHat | python27-python-0:2.7.16-4.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.4 EUS | RedHat | python27-python-jinja2-0:2.6-15.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUS | RedHat | python27-python-0:2.7.16-4.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUS | RedHat | python27-python-jinja2-0:2.6-15.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUS | RedHat | rh-python36-python-0:3.6.9-2.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUS | RedHat | python27-python-0:2.7.16-4.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUS | RedHat | python27-python-jinja2-0:2.6-15.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUS | RedHat | rh-python36-python-0:3.6.9-2.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUS | RedHat | rh-python36-python-0:3.6.9-2.el7 | * |
| Python2.7 | Ubuntu | bionic | * |
| Python2.7 | Ubuntu | trusty | * |
| Python2.7 | Ubuntu | xenial | * |
| Python3.4 | Ubuntu | trusty | * |
| Python3.5 | Ubuntu | trusty | * |
| Python3.5 | Ubuntu | trusty/esm | * |
| Python3.5 | Ubuntu | xenial | * |
| Python3.6 | Ubuntu | bionic | * |
| Python3.7 | Ubuntu | bionic | * |
| Python3.7 | Ubuntu | upstream | * |
PRNGs are deterministic and, while their output appears
random, they cannot actually create entropy. They rely on
cryptographically secure and unique seeds for entropy so
proper seeding is critical to the secure operation of the
PRNG.
Management of seeds could be broken down into two main areas:
PRNGs require a seed as input to generate a stream of
numbers that are functionally indistinguishable from
random numbers. While the output is, in many cases,
sufficient for cryptographic uses, the output of any
PRNG is directly determined by the seed provided as
input. If the seed can be ascertained by a third party,
the entire output of the PRNG can be made known to
them. As such, the seed should be kept secret and
should ideally not be able to be guessed. For example,
the current time may be a poor seed. Knowing the
approximate time the PRNG was seeded greatly reduces
the possible key space.
Seeds do not necessarily need to be unique, but reusing seeds may open up attacks if the seed is discovered.