Vulnerability-Lookup

PYSEC-2026-2843

Vulnerability from pysec - Published: 2026-07-13 14:36 - Updated: 2026-07-13 16:05

Details

Summary

While fuzzing openexr_exrcheck_fuzzer, Valgrind reports a conditional branch depending on uninitialized data inside generic_unpack. This indicates a use of uninitialized memory (CWE-457). The issue is reproducible with the current OSS-Fuzz harness and a single-file PoC.

Details

Environment: - Tooling: valgrind --tool=memcheck --track-origins=yes - Target: openexr_exrcheck_fuzzer - OS: Ubuntu 20.04.6 LTS focal x86_64 - openexr version and Git-commit hash: openexr 3.4.2 | commit fd657e8a41e157e5841c7cc2e2a5efe094b069a1 (grafted, HEAD -> main, origin/main, origin/HEAD)

Function: generic_unpack

Possible root cause (based on observed symptoms): The unpacker is branching on bytes in a scratch buffer that were never written because the decode step didn’t fully populate it. - The first use flagged is in generic_unpack(). That function reads from the decompressed/expanded pixel buffer to scatter data into the framebuffer. A “conditional jump depends on uninitialised value(s)” means it’s consulting bytes in that buffer before they were written. - Valgrind says the uninitialised value “was created by a heap allocation (malloc)”, not the stack: this matches a per-tile/per-scanline decode scratch buffer allocated in exr_decoding_run().

Valgrind Trace (top frames):

==454== Conditional jump or move depends on uninitialised value(s)
==454==    at 0x4539BE: generic_unpack (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x44B85F: exr_decoding_run (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x38BC5F: Imf_4_0::(anonymous namespace)::TileProcess::run_decode(_priv_exr_context_t const*, int, Imf_4_0::FrameBuffer const*, std::__1::vector<Imf_4_0::Slice, std::__1::allocator<Imf_4_0::Slice> > const&) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x388BE1: Imf_4_0::TiledInputFile::Data::readTiles(int, int, int, int, int, int) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x388619: Imf_4_0::TiledInputFile::readTiles(int, int, int, int, int, int) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x353755: Imf_4_0::InputFile::Data::bufferedReadPixels(int, int) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x352286: Imf_4_0::InputFile::readPixels(int) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x3190FA: Imf_4_0::(anonymous namespace)::readMultiPart(Imf_4_0::MultiPartInputFile&, bool, bool) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x314C4D: Imf_4_0::checkOpenEXRFile(char const*, unsigned long, bool, bool, bool) (in /out/openexr_exrcheck_fuzzer)
==454==  Uninitialised value was created by a heap allocation at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)

PoC

In the attached archive, you will find: - The executable used for our tests. - The testcase used to trigger the bug.

To observe the bug, simply run the OSS-Fuzz helper script:

git clone https://github.com/google/oss-fuzz.git
cd oss-fuzz

python3 infra/helper.py build_image openexr
python3 infra/helper.py build_fuzzers --sanitizer=none openexr
python3 infra/helper.py shell openexr

apt update && apt install -y valgrind
ulimit -n 65535
valgrind --tool=memcheck --track-origins=yes /out/openexr_exrcheck_fuzzer /path/to/poc

Impact

Undefined Behavior
Potential crash
Denial of Service

Credit: Aldo Ristori archive0.zip

Update Note:

Other saved testcases from the fuzzing campaign trigger the same underlying bug, but with a different manifestation. So there is one root cause (missing post-decode validation / zero-init before any unpack), with different call-sites. Below there are several archives, formatted like the previous one, that reproduce the other test cases.

Other observed sinks (distinct manifestations of the same bug):

Deep pointers path: generic_unpack_deep_pointers (deep scanline/tiled) archive1.zip

Deep sample table path: unpack_sample_table (deep scanline) archive2.zip

Half conversion path: half_to_float_buffer_f16c via unpack_half_to_float_3chan_planar archive3.zip

Deep compositing: CompositeDeepScanLine::readPixels → ThreadPool::addTask → LineCompositeTask::execute archive4.zip

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

2.0 (Low)


                  
                    CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

Impacted products

Name	purl
openexr	pkg:pypi/openexr

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "openexr",
        "purl": "pkg:pypi/openexr"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.3.0"
            },
            {
              "fixed": "3.3.6"
            },
            {
              "introduced": "3.4.0"
            },
            {
              "fixed": "3.4.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.3.0",
        "3.3.1",
        "3.3.2",
        "3.3.3",
        "3.3.4",
        "3.3.5",
        "3.4.0",
        "3.4.1",
        "3.4.2"
      ]
    }
  ],
  "aliases": [
    "CVE-2025-64181",
    "GHSA-3h9h-qfvw-98hq"
  ],
  "details": "### Summary\nWhile fuzzing `openexr_exrcheck_fuzzer`, Valgrind reports a conditional branch depending on uninitialized data inside `generic_unpack`. This indicates a use of uninitialized memory (CWE-457). The issue is reproducible with the current OSS-Fuzz harness and a single-file PoC.\n\n### Details\n\n**Environment:**\n- Tooling: `valgrind --tool=memcheck --track-origins=yes`\n- Target: `openexr_exrcheck_fuzzer`\n- OS: Ubuntu 20.04.6 LTS focal x86_64\n- openexr version and Git-commit hash: ` openexr 3.4.2 | commit fd657e8a41e157e5841c7cc2e2a5efe094b069a1 (grafted, HEAD -\u003e main, origin/main, origin/HEAD)`\n\nFunction: `generic_unpack`\n\nPossible root cause (based on observed symptoms):\nThe unpacker is branching on bytes in a scratch buffer that were never written because the decode step didn\u2019t fully populate it.\n- The first use flagged is in `generic_unpack()`. That function reads from the decompressed/expanded pixel buffer to scatter data into the framebuffer. A \u201cconditional jump depends on uninitialised value(s)\u201d means it\u2019s consulting bytes in that buffer before they were written.\n- Valgrind says the uninitialised value \u201cwas created by a heap allocation (malloc)\u201d, not the stack: this matches a per-tile/per-scanline decode scratch buffer allocated in `exr_decoding_run()`.\n\n**Valgrind Trace (top frames):**\n```bash\n==454== Conditional jump or move depends on uninitialised value(s)\n==454==    at 0x4539BE: generic_unpack (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x44B85F: exr_decoding_run (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x38BC5F: Imf_4_0::(anonymous namespace)::TileProcess::run_decode(_priv_exr_context_t const*, int, Imf_4_0::FrameBuffer const*, std::__1::vector\u003cImf_4_0::Slice, std::__1::allocator\u003cImf_4_0::Slice\u003e \u003e const\u0026) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x388BE1: Imf_4_0::TiledInputFile::Data::readTiles(int, int, int, int, int, int) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x388619: Imf_4_0::TiledInputFile::readTiles(int, int, int, int, int, int) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x353755: Imf_4_0::InputFile::Data::bufferedReadPixels(int, int) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x352286: Imf_4_0::InputFile::readPixels(int) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x3190FA: Imf_4_0::(anonymous namespace)::readMultiPart(Imf_4_0::MultiPartInputFile\u0026, bool, bool) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x314C4D: Imf_4_0::checkOpenEXRFile(char const*, unsigned long, bool, bool, bool) (in /out/openexr_exrcheck_fuzzer)\n==454==  Uninitialised value was created by a heap allocation at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)\n```\n\n### PoC\nIn the attached archive, you will find:\n- The executable used for our tests.\n- The testcase used to trigger the bug.\n\nTo observe the bug, simply run the OSS-Fuzz helper script:\n```bash\ngit clone https://github.com/google/oss-fuzz.git\ncd oss-fuzz\n\npython3 infra/helper.py build_image openexr\npython3 infra/helper.py build_fuzzers --sanitizer=none openexr\npython3 infra/helper.py shell openexr\n\napt update \u0026\u0026 apt install -y valgrind\nulimit -n 65535\nvalgrind --tool=memcheck --track-origins=yes /out/openexr_exrcheck_fuzzer /path/to/poc\n```\n\n### Impact\n- Undefined Behavior\n- Potential crash\n- Denial of Service\n\n**Credit:** Aldo Ristori\n[archive0.zip](https://github.com/user-attachments/files/23024726/archive0.zip)\n\n\n\n### Update Note:\nOther saved testcases from the fuzzing campaign trigger the same underlying bug, but with a different manifestation. So there is one root cause (missing post-decode validation / zero-init before any unpack), with different call-sites. Below there are several archives, formatted like the previous one, that reproduce the other test cases.\n\n**Other observed sinks (distinct manifestations of the same bug):**\n\n**Deep pointers path:**\ngeneric_unpack_deep_pointers (deep scanline/tiled)\n[archive1.zip](https://github.com/user-attachments/files/23024736/archive1.zip)\n\n\n**Deep sample table path:**\nunpack_sample_table (deep scanline)\n[archive2.zip](https://github.com/user-attachments/files/23024740/archive2.zip)\n\n\n**Half conversion path:**\nhalf_to_float_buffer_f16c via unpack_half_to_float_3chan_planar\n[archive3.zip](https://github.com/user-attachments/files/23024744/archive3.zip)\n\n\n**Deep compositing:**\nCompositeDeepScanLine::readPixels \u2192 ThreadPool::addTask \u2192 LineCompositeTask::execute\n[archive4.zip](https://github.com/user-attachments/files/23024746/archive4.zip)",
  "id": "PYSEC-2026-2843",
  "modified": "2026-07-13T16:05:24.975590Z",
  "published": "2026-07-13T14:36:48.278249Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-3h9h-qfvw-98hq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-64181"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/AcademySoftwareFoundation/openexr"
    },
    {
      "type": "WEB",
      "url": "https://github.com/user-attachments/files/23024726/archive0.zip"
    },
    {
      "type": "WEB",
      "url": "https://github.com/user-attachments/files/23024736/archive1.zip"
    },
    {
      "type": "WEB",
      "url": "https://github.com/user-attachments/files/23024740/archive2.zip"
    },
    {
      "type": "WEB",
      "url": "https://github.com/user-attachments/files/23024744/archive3.zip"
    },
    {
      "type": "WEB",
      "url": "https://github.com/user-attachments/files/23024746/archive4.zip"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/openexr"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-3h9h-qfvw-98hq"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "OpenEXR Makes Use of Uninitialized Memory"
}

CVE-2025-64181 (GCVE-0-2025-64181)

Vulnerability from cvelistv5 – Published: 2025-11-10 21:23 – Updated: 2025-11-12 21:05

Title

OpenEXR Makes Use of Uninitialized Memory

Summary

OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. In versions 3.3.0 through 3.3.5 and 3.4.0 through 3.4.2, while fuzzing `openexr_exrcheck_fuzzer`, Valgrind reports a conditional branch depending on uninitialized data inside `generic_unpack`. This indicates a use of uninitialized memory. The issue can result in undefined behavior and/or a potential crash/denial of service. Versions 3.3.6 and 3.4.3 fix the issue.

Severity

2 (Low)


                        
                          CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-11-12 17:36 UTC

CWE

CWE-457 - Use of Uninitialized Variable

Assigner

GitHub_M mitre root

References

6 references

URL	Tags
https://github.com/AcademySoftwareFoundation/open…	x_refsource_CONFIRM
https://github.com/user-attachments/files/2302472…	x_refsource_MISC
https://github.com/user-attachments/files/2302473…	x_refsource_MISC
https://github.com/user-attachments/files/2302474…	x_refsource_MISC
https://github.com/user-attachments/files/2302474…	x_refsource_MISC
https://github.com/user-attachments/files/2302474…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
AcademySoftwareFoundation	openexr	Affected: >= 3.3.0, < 3.3.6 Affected: >= 3.4.0, < 3.4.3

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-64181",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-11-12T17:36:24.461719Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-11-12T21:05:26.971Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-3h9h-qfvw-98hq"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "openexr",
          "vendor": "AcademySoftwareFoundation",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 3.3.0, \u003c 3.3.6"
            },
            {
              "status": "affected",
              "version": "\u003e= 3.4.0, \u003c 3.4.3"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. In versions 3.3.0 through 3.3.5 and 3.4.0 through 3.4.2, while fuzzing `openexr_exrcheck_fuzzer`, Valgrind reports a conditional branch depending on uninitialized data inside `generic_unpack`. This indicates a use of uninitialized memory. The issue can result in undefined behavior and/or a potential crash/denial of service. Versions 3.3.6 and 3.4.3 fix the issue."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "LOCAL",
            "baseScore": 2,
            "baseSeverity": "LOW",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-457",
              "description": "CWE-457: Use of Uninitialized Variable",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-11-10T21:23:04.248Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-3h9h-qfvw-98hq",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-3h9h-qfvw-98hq"
        },
        {
          "name": "https://github.com/user-attachments/files/23024726/archive0.zip",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/user-attachments/files/23024726/archive0.zip"
        },
        {
          "name": "https://github.com/user-attachments/files/23024736/archive1.zip",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/user-attachments/files/23024736/archive1.zip"
        },
        {
          "name": "https://github.com/user-attachments/files/23024740/archive2.zip",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/user-attachments/files/23024740/archive2.zip"
        },
        {
          "name": "https://github.com/user-attachments/files/23024744/archive3.zip",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/user-attachments/files/23024744/archive3.zip"
        },
        {
          "name": "https://github.com/user-attachments/files/23024746/archive4.zip",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/user-attachments/files/23024746/archive4.zip"
        }
      ],
      "source": {
        "advisory": "GHSA-3h9h-qfvw-98hq",
        "discovery": "UNKNOWN"
      },
      "title": "OpenEXR Makes Use of Uninitialized Memory"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2025-64181",
    "datePublished": "2025-11-10T21:23:04.248Z",
    "dateReserved": "2025-10-28T21:07:16.440Z",
    "dateUpdated": "2025-11-12T21:05:26.971Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

GHSA-3H9H-QFVW-98HQ

Vulnerability from github – Published: 2026-04-06 17:51 – Updated: 2026-04-06 17:51

Summary

OpenEXR Makes Use of Uninitialized Memory

Details

Summary

Details

Function: generic_unpack

Valgrind Trace (top frames):

==454== Conditional jump or move depends on uninitialised value(s)
==454==    at 0x4539BE: generic_unpack (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x44B85F: exr_decoding_run (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x38BC5F: Imf_4_0::(anonymous namespace)::TileProcess::run_decode(_priv_exr_context_t const*, int, Imf_4_0::FrameBuffer const*, std::__1::vector<Imf_4_0::Slice, std::__1::allocator<Imf_4_0::Slice> > const&) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x388BE1: Imf_4_0::TiledInputFile::Data::readTiles(int, int, int, int, int, int) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x388619: Imf_4_0::TiledInputFile::readTiles(int, int, int, int, int, int) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x353755: Imf_4_0::InputFile::Data::bufferedReadPixels(int, int) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x352286: Imf_4_0::InputFile::readPixels(int) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x3190FA: Imf_4_0::(anonymous namespace)::readMultiPart(Imf_4_0::MultiPartInputFile&, bool, bool) (in /out/openexr_exrcheck_fuzzer)
==454==    by 0x314C4D: Imf_4_0::checkOpenEXRFile(char const*, unsigned long, bool, bool, bool) (in /out/openexr_exrcheck_fuzzer)
==454==  Uninitialised value was created by a heap allocation at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)

PoC

In the attached archive, you will find: - The executable used for our tests. - The testcase used to trigger the bug.

To observe the bug, simply run the OSS-Fuzz helper script:

git clone https://github.com/google/oss-fuzz.git
cd oss-fuzz

python3 infra/helper.py build_image openexr
python3 infra/helper.py build_fuzzers --sanitizer=none openexr
python3 infra/helper.py shell openexr

apt update && apt install -y valgrind
ulimit -n 65535
valgrind --tool=memcheck --track-origins=yes /out/openexr_exrcheck_fuzzer /path/to/poc

Impact

Undefined Behavior
Potential crash
Denial of Service

Credit: Aldo Ristori archive0.zip

Update Note:

Other observed sinks (distinct manifestations of the same bug):

Deep pointers path: generic_unpack_deep_pointers (deep scanline/tiled) archive1.zip

Deep sample table path: unpack_sample_table (deep scanline) archive2.zip

Half conversion path: half_to_float_buffer_f16c via unpack_half_to_float_3chan_planar archive3.zip

Deep compositing: CompositeDeepScanLine::readPixels → ThreadPool::addTask → LineCompositeTask::execute archive4.zip

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

2.0 (Low)


                  
                    CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "OpenEXR"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.3.0"
            },
            {
              "fixed": "3.3.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "OpenEXR"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.4.0"
            },
            {
              "fixed": "3.4.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-64181"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-457"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-06T17:51:11Z",
    "nvd_published_at": "2025-11-10T22:15:36Z",
    "severity": "LOW"
  },
  "details": "### Summary\nWhile fuzzing `openexr_exrcheck_fuzzer`, Valgrind reports a conditional branch depending on uninitialized data inside `generic_unpack`. This indicates a use of uninitialized memory (CWE-457). The issue is reproducible with the current OSS-Fuzz harness and a single-file PoC.\n\n### Details\n\n**Environment:**\n- Tooling: `valgrind --tool=memcheck --track-origins=yes`\n- Target: `openexr_exrcheck_fuzzer`\n- OS: Ubuntu 20.04.6 LTS focal x86_64\n- openexr version and Git-commit hash: ` openexr 3.4.2 | commit fd657e8a41e157e5841c7cc2e2a5efe094b069a1 (grafted, HEAD -\u003e main, origin/main, origin/HEAD)`\n\nFunction: `generic_unpack`\n\nPossible root cause (based on observed symptoms):\nThe unpacker is branching on bytes in a scratch buffer that were never written because the decode step didn\u2019t fully populate it.\n- The first use flagged is in `generic_unpack()`. That function reads from the decompressed/expanded pixel buffer to scatter data into the framebuffer. A \u201cconditional jump depends on uninitialised value(s)\u201d means it\u2019s consulting bytes in that buffer before they were written.\n- Valgrind says the uninitialised value \u201cwas created by a heap allocation (malloc)\u201d, not the stack: this matches a per-tile/per-scanline decode scratch buffer allocated in `exr_decoding_run()`.\n\n**Valgrind Trace (top frames):**\n```bash\n==454== Conditional jump or move depends on uninitialised value(s)\n==454==    at 0x4539BE: generic_unpack (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x44B85F: exr_decoding_run (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x38BC5F: Imf_4_0::(anonymous namespace)::TileProcess::run_decode(_priv_exr_context_t const*, int, Imf_4_0::FrameBuffer const*, std::__1::vector\u003cImf_4_0::Slice, std::__1::allocator\u003cImf_4_0::Slice\u003e \u003e const\u0026) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x388BE1: Imf_4_0::TiledInputFile::Data::readTiles(int, int, int, int, int, int) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x388619: Imf_4_0::TiledInputFile::readTiles(int, int, int, int, int, int) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x353755: Imf_4_0::InputFile::Data::bufferedReadPixels(int, int) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x352286: Imf_4_0::InputFile::readPixels(int) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x3190FA: Imf_4_0::(anonymous namespace)::readMultiPart(Imf_4_0::MultiPartInputFile\u0026, bool, bool) (in /out/openexr_exrcheck_fuzzer)\n==454==    by 0x314C4D: Imf_4_0::checkOpenEXRFile(char const*, unsigned long, bool, bool, bool) (in /out/openexr_exrcheck_fuzzer)\n==454==  Uninitialised value was created by a heap allocation at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)\n```\n\n### PoC\nIn the attached archive, you will find:\n- The executable used for our tests.\n- The testcase used to trigger the bug.\n\nTo observe the bug, simply run the OSS-Fuzz helper script:\n```bash\ngit clone https://github.com/google/oss-fuzz.git\ncd oss-fuzz\n\npython3 infra/helper.py build_image openexr\npython3 infra/helper.py build_fuzzers --sanitizer=none openexr\npython3 infra/helper.py shell openexr\n\napt update \u0026\u0026 apt install -y valgrind\nulimit -n 65535\nvalgrind --tool=memcheck --track-origins=yes /out/openexr_exrcheck_fuzzer /path/to/poc\n```\n\n### Impact\n- Undefined Behavior\n- Potential crash\n- Denial of Service\n\n**Credit:** Aldo Ristori\n[archive0.zip](https://github.com/user-attachments/files/23024726/archive0.zip)\n\n\n\n### Update Note:\nOther saved testcases from the fuzzing campaign trigger the same underlying bug, but with a different manifestation. So there is one root cause (missing post-decode validation / zero-init before any unpack), with different call-sites. Below there are several archives, formatted like the previous one, that reproduce the other test cases.\n\n**Other observed sinks (distinct manifestations of the same bug):**\n\n**Deep pointers path:**\ngeneric_unpack_deep_pointers (deep scanline/tiled)\n[archive1.zip](https://github.com/user-attachments/files/23024736/archive1.zip)\n\n\n**Deep sample table path:**\nunpack_sample_table (deep scanline)\n[archive2.zip](https://github.com/user-attachments/files/23024740/archive2.zip)\n\n\n**Half conversion path:**\nhalf_to_float_buffer_f16c via unpack_half_to_float_3chan_planar\n[archive3.zip](https://github.com/user-attachments/files/23024744/archive3.zip)\n\n\n**Deep compositing:**\nCompositeDeepScanLine::readPixels \u2192 ThreadPool::addTask \u2192 LineCompositeTask::execute\n[archive4.zip](https://github.com/user-attachments/files/23024746/archive4.zip)",
  "id": "GHSA-3h9h-qfvw-98hq",
  "modified": "2026-04-06T17:51:11Z",
  "published": "2026-04-06T17:51:11Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-3h9h-qfvw-98hq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-64181"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/AcademySoftwareFoundation/openexr"
    },
    {
      "type": "WEB",
      "url": "https://github.com/user-attachments/files/23024726/archive0.zip"
    },
    {
      "type": "WEB",
      "url": "https://github.com/user-attachments/files/23024736/archive1.zip"
    },
    {
      "type": "WEB",
      "url": "https://github.com/user-attachments/files/23024740/archive2.zip"
    },
    {
      "type": "WEB",
      "url": "https://github.com/user-attachments/files/23024744/archive3.zip"
    },
    {
      "type": "WEB",
      "url": "https://github.com/user-attachments/files/23024746/archive4.zip"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "OpenEXR Makes Use of Uninitialized Memory"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
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Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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PYSEC-2026-2843

Summary

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PoC

Impact

Update Note:

CVE-2025-64181 (GCVE-0-2025-64181)

GHSA-3H9H-QFVW-98HQ

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