CVE-2018-1000030

Python 2.7.14 is vulnerable to a Heap-Buffer-Overflow as well as a Heap-Use-After-Free. Python versions prior to 2.7.14 may also be vulnerable and it appears that Python 2.7.17 and prior may also be vulnerable however this has not been confirmed. The vulnerability lies when multiply threads are handling large amounts of data. In both cases there is essentially a race condition that occurs. For the Heap-Buffer-Overflow, Thread 2 is creating the size for a buffer, but Thread1 is already writing to the buffer without knowing how much to write. So when a large amount of data is being processed, it is very easy to cause memory corruption using a Heap-Buffer-Overflow. As for the Use-After-Free, Thread3->Malloc->Thread1->Free's->Thread2-Re-uses-Free'd Memory. The PSRT has stated that this is not a security vulnerability due to the fact that the attacker must be able to run code, however in some situations, such as function as a service, this vulnerability can potentially be used by an attacker to violate a trust boundary, as such the DWF feels this issue deserves a CVE.

Versions of Python 2 included in Red Hat Enterprise Linux 6 and 7 are affected by this issue. Reading concurrently from the same file handle in multiple threads is inherently unstable, and should not be relied upon in any real program. This issue is not planned to be fixed in future releases.

This CVE assignment was disputed by upstream. While an attack is theoretically possible, it relies on a programming pattern in the vulnerable Python program that is generally considered bad practice if not an outright bug.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.