CVE-2021-29531

CHECK-fail in tf.raw_ops.EncodePng

Severity Score

5.5

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

TensorFlow is an end-to-end open source platform for machine learning. An attacker can trigger a `CHECK` fail in PNG encoding by providing an empty input tensor as the pixel data. This is because the implementation(https://github.com/tensorflow/tensorflow/blob/e312e0791ce486a80c9d23110841525c6f7c3289/tensorflow/core/kernels/image/encode_png_op.cc#L57-L60) only validates that the total number of pixels in the image does not overflow. Thus, an attacker can send an empty matrix for encoding. However, if the tensor is empty, then the associated buffer is `nullptr`. Hence, when calling `png::WriteImageToBuffer`(https://github.com/tensorflow/tensorflow/blob/e312e0791ce486a80c9d23110841525c6f7c3289/tensorflow/core/kernels/image/encode_png_op.cc#L79-L93), the first argument (i.e., `image.flat<T>().data()`) is `NULL`. This then triggers the `CHECK_NOTNULL` in the first line of `png::WriteImageToBuffer`(https://github.com/tensorflow/tensorflow/blob/e312e0791ce486a80c9d23110841525c6f7c3289/tensorflow/core/lib/png/png_io.cc#L345-L349). Since `image` is null, this results in `abort` being called after printing the stacktrace. Effectively, this allows an attacker to mount a denial of service attack. The fix will be included in TensorFlow 2.5.0. We will also cherrypick this commit on TensorFlow 2.4.2, TensorFlow 2.3.3, TensorFlow 2.2.3 and TensorFlow 2.1.4, as these are also affected and still in supported range.

TensorFlow es una plataforma de código abierto de extremo a extremo para el aprendizaje automático. Un atacante puede desencadenar "CHECK" en una codificación PNG al proporcionar un tensor de entrada vacío como datos de píxeles. Esto es debido a que la implementación (https://github.com/tensorflow/tensorflow/blob/e312e0791ce486a80c9d23110841525c6f7c3289/tensorflow/core/kernels/image/encode_png_op.cc#L57-L60) solo comprueba que el número total de píxeles en una imagen no se desborda. Por lo tanto, un atacante puede enviar una matriz vacía para codificar. Sin embargo, si el tensor está vacío, entonces el búfer asociado es "nullptr". Por lo tanto, al llamar a la función "png::WriteImageToBuffer" (https://github.com/tensorflow/tensorflow/blob/e312e0791ce486a80c9d23110841525c6f7c3289/tensorflow/core/kernels/image/encode_png_op.cc#L79-L93), el primer argumento (es decir, "image.flat (T) () .data ()") es "NULL". Esto luego desencadena el "CHECK_NOTNULL" en una primera línea de la función "png::WriteImageToBuffer" (https://github.com/tensorflow/tensorflow/blob/e312e0791ce486a80c9d23110841525c6f7c3289/tensorflow/core/lib/png/png_45-Lcc349L). Dado que "image" es null, esto resulta en que se llame a "abort" después de imprimir el stacktrace. Efectivamente, esto permite a un atacante montar un ataque de denegación de servicio. La corrección será incluida en TensorFlow versión 2.5.0. También seleccionaremos este commit en TensorFlow versión 2.4.2, TensorFlow versión 2.3.3, TensorFlow versión 2.2.3 y TensorFlow versión 2.1.4, ya que estos también están afectados y aún están en el rango compatible

*Credits: N/A

CVSS Scores

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Local

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low

Attack Vector

Local

Attack Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-03-30 CVE Reserved
2021-05-14 CVE Published
2023-03-08 EPSS Updated
2024-08-03 CVE Updated
2024-08-03 First Exploit
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-754: Improper Check for Unusual or Exceptional Conditions

CAPEC

References (2)

URL	Tag	Source

URL	Date	SRC
https://github.com/tensorflow/tensorflow/security/advisories/GHSA-3qxp-qjq7-w4hf	2024-08-03

URL	Date	SRC
https://github.com/tensorflow/tensorflow/commit/26eb323554ffccd173e8a79a8c05c15b685ae4d1	2021-05-20

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Google Search vendor "Google"		Tensorflow Search vendor "Google" for product "Tensorflow"				< 2.1.4 Search vendor "Google" for product "Tensorflow" and version " < 2.1.4"		-		Affected
Google Search vendor "Google"		Tensorflow Search vendor "Google" for product "Tensorflow"				>= 2.2.0 < 2.2.3 Search vendor "Google" for product "Tensorflow" and version " >= 2.2.0 < 2.2.3"		-		Affected
Google Search vendor "Google"		Tensorflow Search vendor "Google" for product "Tensorflow"				>= 2.3.0 < 2.3.3 Search vendor "Google" for product "Tensorflow" and version " >= 2.3.0 < 2.3.3"		-		Affected
Google Search vendor "Google"		Tensorflow Search vendor "Google" for product "Tensorflow"				>= 2.4.0 < 2.4.2 Search vendor "Google" for product "Tensorflow" and version " >= 2.4.0 < 2.4.2"		-		Affected