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How CVE‑2026‑28764 Works
MediaInfoLib is a widely used open‑source C++ library that extracts technical and metadata information from video and audio files. Its LXF (Linear eXtensible Format) element parsing functionality contains a critical heap‑based buffer overflow, identified as CVE‑2026‑28764 and discovered by Cisco Talos. The flaw resides in the `File_Lxf::Header_Parse()` function when processing specially crafted `.lxf` files. The core issue is a typographical error in the source code: the code incorrectly uses `Header_Size` (a macro) instead of the intended `HeaderSize` local variable when calculating how many bytes to skip during parsing. At the point of the vulnerability, the function reads the header size from the file, compares it with the current parser offset, and then attempts to skip the remaining bytes. However, because `Header_Size` is a macro that expands to a member variable (initialised to zero) while the comparison uses the correct local `HeaderSize` variable, the subtraction becomes Header_Size - Element_Offset, which always yields a negative value. This negative value is then passed to Skip_XX(), causing an uncontrolled increment of Element_Offset. As a result, the parser proceeds to write far beyond the allocated heap buffer, leading to memory corruption. An attacker can exploit this by crafting a malicious `.lxf` file that, when processed by any application using the vulnerable version of the library, triggers the overflow. The vulnerability can be leveraged for arbitrary code execution or at least cause a denial‑of‑service crash. The issue affects MediaInfoLib version 26.01 and likely earlier versions up to 18.05. The CVSS 3.1 base score is 7.8 (High), with the vector AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, indicating that an attacker needs only to trick a user into opening a malicious file, and can then gain full control over the confidentiality, integrity, and availability of the system.
DailyCVE Form:
Platform: MediaArea MediaInfoLib
Version: 26.01
Vulnerability: heap buffer overflow
Severity: Critical (7.8)
Date: 2026-05-21
Prediction: 2026-06-15
What Undercode Say
– `CVE‑2026‑28764` MediaInfoLib 26.01 LXF parsing heap overflow
– CVSS 7.8 (High) – `AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`
– Root cause: `Header_Size` vs `HeaderSize` typo in `File_Lxf::Header_Parse()`
– EPSS score: 0.01% (30‑day exploitation probability)
– No public exploit PoC as of now
– Talos advisory: TALOS‑2026‑2371
Check MediaInfoLib version
mediainfo --version
List LXF‑dependent packages (Linux)
apt list --installed | grep -i mediainfo
Find vulnerable .lxf files
find / -name ".lxf" 2>/dev/null
Basic fuzzing with radamsa (Linux)
radamsa -o output_%n.lxf input_seed.lxf
Decompile LXF parser (requires MediaInfoLib source)
objdump -d libmediainfo.so | grep -A 20 "Header_Parse"
Simulated exploit trigger (PoC placeholder)
python3 -c 'print("A"1024)' > poc.lxf
mediainfo poc.lxf
Exploit
An attacker constructs a `.lxf` file with a malformed header. The header specifies a large `HeaderSize` value that exceeds the current parser offset. Because `Header_Size` is zero, the subtraction `Header_Size – Element_Offset` becomes negative. The `Skip_XX()` function then advances `Element_Offset` by this negative value, effectively moving the parser backward. Subsequent operations write data into a heap buffer at an index that is now far outside the originally allocated bounds, overwriting adjacent heap metadata and potentially function pointers. By carefully controlling the overwritten data, an attacker can redirect code execution to a malicious payload embedded in the file. Successful exploitation leads to arbitrary code execution with the privileges of the process using the library. The attached `poc.lxf` (not yet publicly available) demonstrates a heap overflow, resulting in a crash or, with further tuning, a full remote code execution chain.
Protection
- Update MediaInfoLib to the latest version as soon as a patch is released by MediaArea (expected around 2026‑06‑15).
- If an update is unavailable, disable or remove the LXF element parsing feature, or restrict the library to process only trusted media sources.
- Employ runtime mitigations: ASLR, stack canaries, and compile‑time address sanitizers.
- Use a web application firewall (e.g., BitNinja) to block malicious `.lxf` traffic.
- Implement sandboxed processing environments for untrusted media files.
- Monitor server logs for unusual activity and regularly scan for vulnerable versions.
Impact
Successful exploitation of CVE‑2026‑28764 can lead to arbitrary code execution on the target system, allowing an attacker to gain full control of the affected application. Consequences range from denial of service (application crash) to total system compromise, including unauthorised access to sensitive information, privilege escalation, and persistent malware installation. The vulnerability poses a significant risk to any system that processes untrusted media files using MediaInfoLib, such as media management software, content analysis tools, digital asset management platforms, and online file upload services. Although no active exploitation has been confirmed yet, the high CVSS score and the ease of triggering the overflow make this a critical issue that requires immediate attention.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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