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CVE-2024-38949 is a heap buffer overflow vulnerability affecting the libde265 HEVC/H.265 video codec library version 1.0.15 and prior.
The flaw specifically resides in the display444as420 function located within sdl.cc.
When parsing a maliciously crafted HEVC video stream or payload, the library fails to properly validate and bound buffer sizes during color space conversion routines.
Specifically, when converting chroma subsampling formats from 4:4:4 to 4:2:0, the internal memory allocation routines compute incorrect destination buffer dimensions.
This mismatch between the expected and actual memory required for pixel row storage leads to an out-of-bounds write condition on the heap.
An attacker can leverage this weakness by supplying a specially formatted HEVC media file to an application utilizing libde265 for video decoding.
When the vulnerable function processes the crafted payload, heap metadata structures adjacent to the video buffer can be overwritten.
This memory corruption compromises the integrity of the heap manager and can be manipulated to achieve arbitrary code execution or a denial of service state.
Because video decoding libraries often process untrusted user-supplied files automatically in media players, web browsers, or thumbnail generators, the attack surface is broad.
Exploitation typically does not require authentication, relying entirely on the victim opening or rendering the malicious media file.
Debugging sessions reveal that improper bounds checking on input width and height parameters during pixel array reallocation triggers the overflow.
Without strict input validation on color format transformation parameters, malicious actors can inject arbitrary data past the boundary of the allocated heap chunk.
Mitigation requires updating libde265 to patched versions where robust boundary checks and safe integer arithmetic are enforced prior to buffer allocation.
DailyCVE Form:
Platform: Libde265
Version: v1.0.15
Vulnerability: Heap Buffer Overflow
Severity: Moderate
date: June 26, 2024
Prediction: July 2024 patch
What Undercode Say
Clone repository and check vulnerable version git clone https://github.com/strukturag/libde265.git cd libde265 git checkout v1.0.15 Compile with AddressSanitizer to detect heap corruption mkdir build && cd build cmake -DCMAKE_C_FLAGS="-fsanitize=address" -DCMAKE_CXX_FLAGS="-fsanitize=address" .. make -j$(nproc) Run decoder against crafted payload to trigger CVE-2024-38949 ./dec265 malicious_payload.bin
Exploit: (Educational Purposes!)
The proof-of-concept exploit involves constructing a malformed HEVC bitstream where the Sequence Parameter Set (SPS) or slice headers declare dimensions that mismatch the actual pixel buffer allocation in `display444as420` within sdl.cc. When the decoder processes the conversion from 4:4:4 color space to 4:2:0, the loop writes past the heap chunk boundaries. Attackers craft the payload header to control the exact overflow bytes, aiming to overwrite adjacent heap chunks or function pointers to hijack control flow.
Protection: from this CVE
To protect systems against CVE-2024-38949, administrators and developers must upgrade the libde265 library to version 1.0.19 or later, or apply the official security patches provided by downstream distributions (such as Debian and Ubuntu security updates). Additionally, implementing robust input sanitization and fuzzing pipelines for media parsers can prevent similar memory corruption flaws.
Impact:
Successful exploitation of this vulnerability leads to application crashes resulting in a Denial of Service (DoS). In more sophisticated scenarios involving heap manipulation, attackers can achieve arbitrary code execution within the security context of the user running the media processing application, potentially compromising system confidentiality and integrity.
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Sources:
Reported By: github.com
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