CVE-2021-41217: Null pointer exception when `Exit` node is not preceded by `Enter` op

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-11-05 · updated 2026-06-17
Weakness: CWE-476

Description

TensorFlow is an open source platform for machine learning. In affected versions the process of building the control flow graph for a TensorFlow model is vulnerable to a null pointer exception when nodes that should be paired are not. This occurs because the code assumes that the first node in the pairing (e.g., an `Enter` node) always exists when encountering the second node (e.g., an `Exit` node). When this is not the case, `parent` is `nullptr` so dereferencing it causes a crash. The fix will be included in TensorFlow 2.7.0. We will also cherrypick this commit on TensorFlow 2.6.1, TensorFlow 2.5.2, and TensorFlow 2.4.4, as these are also affected and still in supported range.

Affected products

tensorflow: before 2.4.4; from 2.5.0 before 2.5.2; 2.6.0 — fixed in 2.4.4, 2.5.2

How to fix

Upgrade to a fixed version: tensorflow 2.4.4, 2.5.2. Check the vendor advisory for mitigations.

References

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