How severe is GHSA-3h9h-qfvw-98hq?

GHSA-3h9h-qfvw-98hq has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-3h9h-qfvw-98hq?

GHSA-3h9h-qfvw-98hq affects the following packages: openexr (PyPI), openexr (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-3h9h-qfvw-98hq?

Update openexr to 3.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3h9h-qfvw-98hq is resolved across your whole dependency graph.

How do I detect GHSA-3h9h-qfvw-98hq in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openexr. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-3h9h-qfvw-98hq if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-3h9h-qfvw-98hq?

O3 pinpoints whether GHSA-3h9h-qfvw-98hq is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-3h9h-qfvw-98hq actively exploited in the wild?

No public exploit code has been indexed for GHSA-3h9h-qfvw-98hq yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-3h9h-qfvw-98hq?

GHSA-3h9h-qfvw-98hq has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 25th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was GHSA-3h9h-qfvw-98hq published, and has it been updated?

GHSA-3h9h-qfvw-98hq was published on April 6, 2026 and was last updated on April 6, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

GHSA-3h9h-qfvw-98hq

HIGH

OpenEXR Makes Use of Uninitialized Memory

Also known asCVE-2025-64181

Published

Apr 6, 2026

Updated

Apr 6, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk25th percentile+0.22%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

2 pkgs affected

🐍openexr🐍openexr

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`openexr`	≥ 3.3.0&&< 3.3.6	3.3.6
🐍PyPI	`openexr`	≥ 3.4.0&&< 3.4.3	3.4.3

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openexr. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update openexr to 3.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3h9h-qfvw-98hq is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-3h9h-qfvw-98hq is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-3h9h-qfvw-98hq. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### 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/H

O3 Security · Impact-Aware SCA

Is GHSA-3h9h-qfvw-98hq in your dependencies?

O3 detects GHSA-3h9h-qfvw-98hq across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works