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OpenEXR Out of Bounds Heap Read due to Bad Pointer Arithmetic in LossyDctDecoder_execute

Moderate severity GitHub Reviewed Published Jul 31, 2025 in AcademySoftwareFoundation/openexr • Updated Aug 1, 2025

Package

pip OpenEXR (pip)

Affected versions

= 3.3.2

Patched versions

3.3.3

Description

Summary

The OpenEXRCore code is vulnerable to a heap-based buffer overflow during a read operation due to bad pointer math when decompressing DWAA-packed scan-line EXR files with a maliciously forged chunk.

Details

In the LossyDctDecoder_execute function (from src/lib/OpenEXRCore/internal_dwa_decoder.h, when SSE2 is enabled), the following code is used to copy data from the chunks:

// no-op conversion to linear
for (int y = 8 * blocky; y < 8 * blocky + maxY; ++y)
{
    __m128i* restrict dst = (__m128i *) chanData[comp]->_rows[y];
    __m128i const * restrict src = (__m128i const *)&rowBlock[comp][(y & 0x7) * 8];

    for (int blockx = 0; blockx < numFullBlocksX; ++blockx)
    {
        _mm_storeu_si128 (dst, _mm_loadu_si128 (src)); //

        src += 8 * 8; // <--- si128 pointer incremented as a uint16_t
        dst += 8;
    }
}

The issue arises because the src pointer, which is a si128 pointer, is incremented by 8*8, as if it were a uint16_t pointer (64 * uint16_t == 128 bytes). In non-block aligned chunks (width/height not a multiple of 8), this can cause src to point past the boundaries of the chunk.

PoC

In order to reproduce the PoC with fidelity and avoid undefined behaviors, it is necessary to enable ASAN (and SSE2). Otherwise the out-of-bound read will not be detected until its side-effect causes a crash.

NOTE: please download the dwadecoder_crash.exr file from the following link:

https://github.com/ShielderSec/poc/tree/main/CVE-2025-48072

  1. Compile the exrcheck binary in a macOS or GNU/Linux machine with ASAN.
  2. Open the dwadecoder_crash.exr file with the following command:
exrcheck dwadecoder_crash.exr
  1. Notice that exrcheck crashes with ASAN stack-trace.
==2297956==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x52500000a110 at pc 0x55e590db7bf1 bp 0x7fff948bb110 sp 0x7fff948bb108
READ of size 16 at 0x52500000a110 thread T0
    #0 0x55e590db7bf0 in LossyDctDecoder_execute /root/openexr/src/lib/OpenEXRCore/internal_dwa_decoder.h:650:48
    #1 0x55e590dae18d in DwaCompressor_uncompress /root/openexr/src/lib/OpenEXRCore/internal_dwa_compressor.h:1132:30
    #2 0x55e590da9960 in internal_exr_undo_dwaa /root/openexr/src/lib/OpenEXRCore/internal_dwa.c:202:18
    #3 0x55e590d42d03 in exr_uncompress_chunk /root/openexr/src/lib/OpenEXRCore/compression.c:516:14
    #4 0x55e590dc3132 in exr_decoding_run /root/openexr/src/lib/OpenEXRCore/decoding.c:580:14
    #5 0x55e590c7d78f in Imf_3_4::(anonymous namespace)::ScanLineProcess::run_decode(_priv_exr_context_t const*, int, Imf_3_4::FrameBuffer const*, int, int, std::vector<Imf_3_4::Slice, std::allocator<Imf_3_4::Slice>> const&) /root/openexr/src/lib/OpenEXR/ImfScanLineInputFile.cpp:585:23
    #6 0x55e590c83ed7 in Imf_3_4::ScanLineInputFile::Data::readPixels(Imf_3_4::FrameBuffer const&, int, int) /root/openexr/src/lib/OpenEXR/ImfScanLineInputFile.cpp:499:21
    #7 0x55e590c73c97 in Imf_3_4::ScanLineInputFile::readPixels(int, int) /root/openexr/src/lib/OpenEXR/ImfScanLineInputFile.cpp:306:12
    #8 0x55e590c73c97 in Imf_3_4::InputFile::Data::readPixels(int, int) /root/openexr/src/lib/OpenEXR/ImfInputFile.cpp:446:20
    #9 0x55e590c1f92f in Imf_3_4::InputFile::readPixels(int) /root/openexr/src/lib/OpenEXR/ImfInputFile.cpp:228:12
    #10 0x55e590c1f92f in Imf_3_4::InputPart::readPixels(int) /root/openexr/src/lib/OpenEXR/ImfInputPart.cpp:70:11
    #11 0x55e590c1f92f in bool Imf_3_4::(anonymous namespace)::readScanline<Imf_3_4::InputPart>(Imf_3_4::InputPart&, bool, bool) /root/openexr/src/lib/OpenEXRUtil/ImfCheckFile.cpp:239:20
    #12 0x55e590c1f92f in Imf_3_4::(anonymous namespace)::readMultiPart(Imf_3_4::MultiPartInputFile&, bool, bool) /root/openexr/src/lib/OpenEXRUtil/ImfCheckFile.cpp:879:28
    #13 0x55e590c155af in bool Imf_3_4::(anonymous namespace)::runChecks<char const*>(char const*&, bool, bool) /root/openexr/src/lib/OpenEXRUtil/ImfCheckFile.cpp:1132:21
    #14 0x55e590c155af in Imf_3_4::checkOpenEXRFile(char const*, bool, bool, bool) /root/openexr/src/lib/OpenEXRUtil/ImfCheckFile.cpp:1796:19
    #15 0x55e590ba5abe in exrCheck(char const*, bool, bool, bool, bool) /root/openexr/src/bin/exrcheck/main.cpp:96:16
    #16 0x55e590ba6fbe in main /root/openexr/src/bin/exrcheck/main.cpp:164:29
    #17 0x7f4259e2a1c9 in __libc_start_call_main csu/../sysdeps/npthttps://gitlab.com/qemu-project/qemu/-/issuesl/libc_start_call_main.h:58:16
    #18 0x7f4259e2a28a in __libc_start_main csu/../csu/libc-start.c:360:3
    #19 0x55e590ac67d4 in _start (/root/openexr/_build_afl_asan/bin/exrcheck+0x1d87d4) (BuildId: 49c2658b2f9ddef9)

0x52500000a110 is located 752 bytes after 9504-byte region [0x525000007900,0x525000009e20)
allocated by thread T0 here:
    #0 0x55e590b61623 in malloc (/root/openexr/_build_afl_asan/bin/exrcheck+0x273623) (BuildId: 49c2658b2f9ddef9)
    #1 0x55e590db11b1 in LossyDctDecoder_execute /root/openexr/src/lib/OpenEXRCore/internal_dwa_decoder.h:324:22
    #2 0x55e590dae18d in DwaCompressor_uncompress /root/openexr/src/lib/OpenEXRCore/internal_dwa_compressor.h:1132:30
    #3 0x55e590da9960 in internal_exr_undo_dwaa /root/openexr/src/lib/OpenEXRCore/internal_dwa.c:202:18
    #4 0x55e590d42d03 in exr_uncompress_chunk /root/openexr/src/lib/OpenEXRCore/compression.c:516:14

Impact

An attacker could crash the application and in some scenarios also leak data, such as sensitive information or memory addresses that might be used to bypass exploitation mitigations like ASLR.

References

@cary-ilm cary-ilm published to AcademySoftwareFoundation/openexr Jul 31, 2025
Published to the GitHub Advisory Database Jul 31, 2025
Reviewed Jul 31, 2025
Published by the National Vulnerability Database Jul 31, 2025
Last updated Aug 1, 2025

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Local
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction Active
Vulnerable System Impact Metrics
Confidentiality High
Integrity None
Availability High
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(10th percentile)

Weaknesses

Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer. Learn more on MITRE.

CVE ID

CVE-2025-48072

GHSA ID

GHSA-4r7w-q3jg-ff43

Source code

Credits

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