Security advisory

{
  "id": "df3d66672c5571cb4ef8776c28a076a5d1c93d2de8524e3f7394ff45192e63e2",
  "url": "https://osv.dev/vulnerability/CVE-2021-29531",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-29531",
    "summary": "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().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.",
    "evidence": "osv:CVE-2021-29531",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-29531",
      "aliases": [
        "BIT-tensorflow-2021-29531",
        "CVE-2021-29531",
        "GHSA-3qxp-qjq7-w4hf",
        "PYSEC-2021-168",
        "PYSEC-2021-459",
        "PYSEC-2021-657"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/tensorflow/tensorflow",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "0931ea3d985bb9c8fdd054a5e29c4129623c849b"
                },
                {
                  "introduced": "2b96f3662bd776e277f86997659e61046b56c315"
                },
                {
                  "fixed": "cfe0c80169ae984bcdc99ff6de7444164aaa8e07"
                },
                {
                  "introduced": "b36436b087bd8e8701ef51718179037cccdfc26e"
                },
                {
                  "fixed": "3929ffacfbef7c431e8397920d040aaf47acff19"
                },
                {
                  "introduced": "582c8d236cb079023657287c318ff26adb239002"
                },
                {
                  "fixed": "1923123d32ea41d92b70a27a3f6ecf0763b56f6c"
                },
                {
                  "fixed": "26eb323554ffccd173e8a79a8c05c15b685ae4d1"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:google:tensorflow:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.1.4"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:google:tensorflow:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "2.2.0"
                      },
                      {
                        "fixed": "2.2.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:google:tensorflow:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "2.3.0"
                      },
                      {
                        "fixed": "2.3.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:google:tensorflow:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "2.4.0"
                      },
                      {
                        "fixed": "2.4.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "26eb323554ffccd173e8a79a8c05c15b685ae4d1"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.1.3",
            "v2.2.2",
            "v2.3.2",
            "v2.4.1",
            "v2.1.2",
            "v2.2.1",
            "v2.4.0",
            "v2.3.1",
            "v2.2.0",
            "v2.1.1",
            "v2.3.0",
            "v2.1.0",
            "v2.1.0-rc0",
            "v2.1.0-rc2",
            "v2.1.0-rc1",
            "v1.12.1",
            "v1.9.0-rc2",
            "v1.6.0-rc1",
            "v1.1.0-rc2",
            "v1.1.0-rc1",
            "0.6.0",
            "0.5.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-29531.json",
            "vanir_signatures": [
              {
                "id": "CVE-2021-29531-b20a3e75",
                "digest": {
                  "threshold": 0.9,
                  "line_hashes": [
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                    "64132955388983408052797715143494939395"
                  ]
                },
                "source": "https://github.com/tensorflow/tensorflow/commit/26eb323554ffccd173e8a79a8c05c15b685ae4d1",
                "target": {
                  "file": "tensorflow/core/kernels/image/encode_png_op.cc"
                },
                "deprecated": false,
                "signature_type": "Line",
                "signature_version": "v1"
              }
            ],
            "vanir_signatures_modified": "2026-10-20T14:24:24Z"
          }
        }
      ],
      "modified": "2026-10-20T14:24:24.870363595Z",
      "provider": "osv",
      "references": [
        "https://github.com/tensorflow/tensorflow/commit/26eb323554ffccd173e8a79a8c05c15b685ae4d1",
        "https://github.com/tensorflow/tensorflow/security/advisories/GHSA-3qxp-qjq7-w4hf"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-29531",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 388906,
  "published_at": "2021-05-14T20:15:12.027+00:00"
}