PyYAML 5.1 through 5.1.2 has insufficient restrictions on the load and load_all functions because of a class deserialization issue, e.g., Popen is a class in the subprocess module. NOTE: this issue exists because of an incomplete fix for CVE-2017-18342.
Weakness
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Pyyaml | Pyyaml | 5.1 (including) | 5.1.2 (including) |
| Red Hat Enterprise Linux 8 | RedHat | python38:3.8-8030020200818121840.4190259b | * |
| Red Hat Quay 3 | RedHat | quay/clair-rhel8:v3.4.0-25 | * |
| Red Hat Quay 3 | RedHat | quay/quay-bridge-operator-bundle:v3.4.0-3 | * |
| Red Hat Quay 3 | RedHat | quay/quay-bridge-operator-rhel8:v3.4.0-17 | * |
| Red Hat Quay 3 | RedHat | quay/quay-builder-qemu-rhcos-rhel8:v3.4.0-17 | * |
| Red Hat Quay 3 | RedHat | quay/quay-builder-rhel8:v3.4.0-18 | * |
| Red Hat Quay 3 | RedHat | quay/quay-container-security-operator-bundle:v3.4.0-2 | * |
| Red Hat Quay 3 | RedHat | quay/quay-container-security-operator-rhel8:v3.4.0-2 | * |
| Red Hat Quay 3 | RedHat | quay/quay-openshift-bridge-rhel8-operator:v3.4.0-17 | * |
| Red Hat Quay 3 | RedHat | quay/quay-operator-bundle:v3.4.0-89 | * |
| Red Hat Quay 3 | RedHat | quay/quay-operator-rhel8:v3.4.0-132 | * |
| Red Hat Quay 3 | RedHat | quay/quay-rhel8:v3.4.0-51 | * |
| Pyyaml | Ubuntu | eoan | * |
| Pyyaml | Ubuntu | trusty | * |
Potential Mitigations
- Make fields transient to protect them from deserialization.
- An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.
Related Attack Patterns
References
- https://github.com/yaml/pyyaml/blob/master/CHANGES
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H/
- https://www.exploit-db.com/download/47655
- https://github.com/yaml/pyyaml/blob/master/CHANGES
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H/
- https://www.exploit-db.com/download/47655