A deserialization of untrusted data vulnerability was identified in GitHub Enterprise Server that could potentially lead to remote code execution on the SVNBridge. To exploit this vulnerability, an attacker would need to gain access via a server-side request forgery (SSRF) that would let an attacker control the data being deserialized. This vulnerability affected all versions of GitHub Enterprise Server prior to v3.6 and was fixed in versions 3.5.3, 3.4.6, 3.3.11, and 3.2.16. This vulnerability was reported via the GitHub Bug Bounty program.
The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Enterprise_server | Github | * | 3.2.16 (excluding) |
| Enterprise_server | Github | 3.3.0 (including) | 3.3.11 (excluding) |
| Enterprise_server | Github | 3.4.0 (including) | 3.4.6 (excluding) |
| Enterprise_server | Github | 3.5.0 (including) | 3.5.3 (excluding) |
It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security – which is a dangerous security assumption. Data that is untrusted can not be trusted to be well-formed. When developers place no restrictions on “gadget chains,” or series of instances and method invocations that can self-execute during the deserialization process (i.e., before the object is returned to the caller), it is sometimes possible for attackers to leverage them to perform unauthorized actions, like generating a shell.