CVE-2021-41215: 
Python vulnerability analysis and mitigation

TensorFlow, an open source platform for machine learning, disclosed a vulnerability (CVE-2021-41215) in the shape inference code for DeserializeSparse operation. The vulnerability was discovered and reported by members of the Aivul Team from Qihoo 360, and was publicly disclosed on November 4, 2021. The issue affects TensorFlow versions prior to 2.7.0, including versions 2.6.x, 2.5.x, and 2.4.x (GitHub Advisory).

The vulnerability stems from an assumption in the shape inference function that the serialize_sparse tensor is a tensor with positive rank (and having 3 as the last dimension). However, when provided with a scalar input (rank 0), the function can trigger a null pointer dereference. This occurs because the shape inference code fails to properly validate the input tensor's rank (GitHub Advisory).

When exploited, this vulnerability can cause the TensorFlow application to crash due to a null pointer dereference, potentially leading to a denial of service condition (GitHub Advisory).

The issue has been patched in TensorFlow 2.7.0. The fix has also been backported to TensorFlow versions 2.6.1, 2.5.2, and 2.4.4. Users are advised to upgrade to these patched versions to mitigate the vulnerability. The fix involves adding proper rank validation for the input tensor (GitHub Advisory, GitHub Commit).