--- id: CVE-2025-64181 aliases: - GHSA-3h9h-qfvw-98hq - PYSEC-2026-2843 title: OpenEXR Makes Use of Uninitialized Memory summary: OpenEXR Makes Use of Uninitialized Memory severity: high cvss: 7.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H' vendor: openexr product: openexr ecosystem: pip affected: - 'openexr >= 3.3.0, < 3.3.6' - 'openexr >= 3.4.0, < 3.4.3' patched: - openexr 3.3.6 - openexr 3.4.3 published: '2026-04-06' updated: '2026-07-13' source: OSV sourceUrl: 'https://osv.dev/vulnerability/GHSA-3h9h-qfvw-98hq' references: - url: >- https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-3h9h-qfvw-98hq - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-64181' - url: 'https://github.com/AcademySoftwareFoundation/openexr' - url: 'https://github.com/user-attachments/files/23024726/archive0.zip' - url: 'https://github.com/user-attachments/files/23024736/archive1.zip' - url: 'https://github.com/user-attachments/files/23024740/archive2.zip' - url: 'https://github.com/user-attachments/files/23024744/archive3.zip' - url: 'https://github.com/user-attachments/files/23024746/archive4.zip' tags: - osv - pip epss: 0.00382 epssPercentile: 0.32102 ingestedAt: '2026-07-13T18:57:51.896Z' --- ## Overview ### 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):** ```bash ==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 > 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: ```bash 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](https://github.com/user-attachments/files/23024726/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](https://github.com/user-attachments/files/23024736/archive1.zip) **Deep sample table path:** unpack_sample_table (deep scanline) [archive2.zip](https://github.com/user-attachments/files/23024740/archive2.zip) **Half conversion path:** half_to_float_buffer_f16c via unpack_half_to_float_3chan_planar [archive3.zip](https://github.com/user-attachments/files/23024744/archive3.zip) **Deep compositing:** CompositeDeepScanLine::readPixels → ThreadPool::addTask → LineCompositeTask::execute [archive4.zip](https://github.com/user-attachments/files/23024746/archive4.zip) ## Affected packages - `openexr >= 3.3.0, < 3.3.6` - `openexr >= 3.4.0, < 3.4.3` ## Remediation Upgrade to a patched release: - `openexr 3.3.6` - `openexr 3.4.3`