CVE-2026-25104

Executive Summary

CVE-2026-25104 is a heap-based buffer overflow vulnerability in the LXF (LeCroy eXtended Format) file parser component of MediaArea MediaInfoLib, a widely-used open-source media analysis library. Successful exploitation allows an attacker to achieve arbitrary code execution with the privileges of the victim process, potentially enabling remote code execution when MediaInfoLib is embedded in server-side applications or triggered via malicious file processing workflows. The vulnerability carries a CVSS score of 7.8 (High), and at the time of analysis, there is no known vendor patch, no CISA KEV listing, and no public exploit code — however, the unpatched status combined with the library's broad deployment in security products means the risk of weaponization is elevated.

Technical Analysis

The vulnerability resides in the LXF parsing module within MediaInfoLib. LXF is a proprietary binary format used by Teledyne LeCroy oscilloscopes for waveform data. The MediaInfoLib parser processes LXF files by reading a series of headers and records, performing heap memory allocation and subsequent copy operations based on values extracted from the file itself.

The root cause is a heap-based buffer overflow triggered during the parse of the LXF container. Specifically, the parser reads a variable-length data block from the file and allocates a heap buffer with a size derived from a header field. However, the code fails to validate that the actual data length being read into this buffer does not exceed the allocated size. An attacker-controlled value in the file header can cause the parser to write beyond the heap boundary, corrupting adjacent heap metadata.

The overflow condition manifests during the copy operation when memcpy or similar write routine is invoked with a source length that exceeds the allocated destination buffer capacity. The heap metadata corruption can subsequently be abused during memory allocation/deallocation routines to achieve arbitrary write primitives — a common prerequisite for achieving code execution in heap-based overflow exploitation.

The attack surface is significant: MediaInfoLib is embedded in hundreds of applications and services, including:

• FFmpeg-based media servers and transcoding pipelines
• DLNA media servers (e.g., Plex, JRiver)
• Android media metadata scrapers
• VirusTotal and other malware sandboxing platforms
• Email security gateways that parse attachments
• Content management systems with video/audio upload features

An attacker can deliver the malicious LXF file via any standard file-transmission vector: email attachment, HTTP upload, SMB share, USB drive, or web download. The parser is invoked automatically when the file is scanned, indexed, or processed by any of the aforementioned platforms — making this a "file-based zero-click" attack in many deployment contexts.

The vulnerability is classified as unpatched (patch confidence 0/4), meaning no upstream fix or vendor advisory has been released. This absence of a patch, combined with the parser's presence in network-adjacent services, elevates this to a priority monitoring item for enterprise defenders.

Exploitation Scenarios

The following attack chain assumes target identification and weaponization of the heap overflow in an environment where MediaInfoLib processes user-uploaded files.

Step 1 — Reconnaissance and Target Identification. An attacker identifies a target server running a media-processing service known to embed MediaInfoLib. This can be achieved via:

• Banner grabbing on HTTP services (e.g., detecting Plex, Jellyfin, or custom media APIs)
• Shodan search for media server default ports (32400/Plex, 8096/Jellyfin)
• Email infrastructure probing to determine attachment-scanning behavior (e.g., sending benign LXF files and observing if the file is flagged/processed)

Step 2 — Malicious File Construction. Using a legitimate LXF file as a template, the attacker crafts the malicious sample with a hex editor or scripting tool (Python struct module):

• Locate the header field that specifies the destination heap buffer size (e.g., a 32-bit integer at a fixed offset in the header)
• Modify this field to a small allocation size (e.g., 16 bytes) to force a small heap buffer
• Set the subsequent data-length field (or directly embed a large data block) to a large value (e.g., 0xFFFF) that will be copied into this undersized buffer
• Optionally append a ROP chain or shellcode blob after the overflow boundary — or, if more sophisticated, position heap grooming chunks and fake vtable pointers for corrupting a subsequent allocation to hijack control flow

Step 3 — Delivery and Trigger Delivery. The attacker places the crafted .lxf file in a location where the target will parse it:

• Upload the file to a public-facing media server via HTTP POST or the server's API
• Attach the file to an email targeting the organization's mail gateway if the gateway runs attachment-media analysis
• Place the file in an SMB share monitored by a DLP or scanning service

When the target service processes the file (e.g., generating thumbnails/probe metadata), MediaInfoLib's LXF parser executes. The overflow triggers during the record-copy phase, corrupting heap metadata.

Step 4 — Payload Execution and Post-Exploitation. Following heap corruption, the attacker allocates a fake object containing a function pointer table that redirects execution to attacker-controlled data (either embedded in the overflow bytes or in a staged second allocation). Execution is redirected to:

• A classic Win32/x64 shellcode spawning a reverse shell (e.g., msfvenom -p windows/x64/meterpreter/reverse_tcp)
• A Linux ELF shellcode for spawning /bin/sh over a TCP socket
• A DLL side-loading payload if running within a Windows service context

On successful code execution, the attacker inherits the privileges of the media-processing service (often a service account with moderate to high local privileges). Blast radius includes:

• Server-side compromise: The attacker can read/write files accessible to the service account, pivot to the local network, and install persistence mechanisms (e.g., scheduled tasks, cron jobs)
• Sandbox escape risk: If MediaInfoLib is running inside a malware-analysis sandbox (e.g., VirusTotal), the overflow could be used to escape the sandbox and compromise the host
• Data exfiltration: Access to files uploaded to the media server, plus the ability to serve malicious content back to clients

Impact Assessment

CVSS Score Analysis: 7.8 (High). While the exact CVSS vector is unknown, the base score classification implies High severity. The typical composition of a 7.8 score includes a high impact to confidentiality, integrity, and availability (C:H/I:H/A:H). The lack of an explicit remote vector in the score suggests the primary exploitation path is local-file processing (AV:L), which is consistent with the library's design. However, in practical deployment, local file processing becomes remotely triggerable when embedded in services that accept network-supplied files.

Business Impact:

• Confidentiality: An attacker achieving code execution can read sensitive files, database credentials, and media content processed by the vulnerable service
• Integrity: Full control over the affected system allows tampering with all data stored or processed
• Availability: Code execution can force denial-of-service by crashing the service or installing destructive payloads. A simple, non-weaponized crash (segfault due to heap corruption) is also trivially achievable, enabling DoS via malicious file upload even without sophisticated exploitation

Affected Systems: All systems running vulnerable versions of MediaInfoLib — the full affected version range is currently unknown, but older versions are presumed affected. Since no patched version exists, every deployment is considered vulnerable at the time of writing.

Blast Radius: High. MediaInfoLib is a transitive dependency in thousands of products. Any application that automatically parses media files on untrusted input is exposed. This includes cloud file-storage indexing services, email gateways, security scanners, and content management systems.

Detection Guidance

Sigma Rule

title: Suspicious LXF File Parsing Activity - Potential CVE-2026-25104 Exploitation
id: 47e22091-2310-4a44-b2ae-0146a4d3b9cc
status: experimental
description: Detects crashes or anomalous heap-related errors in processes linked against MediaInfoLib when processing LXF files, indicating possible exploitation of CVE-2026-25104.
author: Valters IT Security Team
date: 2026/05/15
tags:
    - attack.execution
    - attack.t1203
    - cve.2026.25104
logsource:
    product: windows
    category: process_creation
detection:
    selection_crash:
        Image|endswith:
            - '\ffmpeg.exe'
            - '\mediainfo.exe'
            - '\Plex Media Server.exe'
            - '\jellyfin.exe'
        CommandLine|contains:
            - '.lxf'
            - 'lxr'
            - 'lxf'
    selection_error:
        # Application Error / Windows Error Reporting
        - EventID: 1000
          Description|contains: 'heap'
        - EventID: 1001
          Description|contains|all:
              - 'media'
              - 'crash'
    condition: selection_crash or selection_error
    falsepositives:
        - Legitimate parsing of LXF files from trusted sources
level: high

YARA Rule

rule CVE_2026_25104_LXF_Heap_Overflow_Indicators
{
    meta:
        author = "Valters IT Security Team"
        description = "Detects LXF files containing anomalous header size fields indicative of CVE-2026-25104 heap overflow exploit attempts."
        date = "2026-05-15"
        reference = "CVE-2026-25104"
        severity = "high"

    strings:
        $lxf_magic = { 4C 45 43 52 4F 59 } // "LECROY" or similar vendor string
        $lxf_magic2 = { 4C 58 46 } // "LXF"
        $huge_size = { FF FF FF 7F } // 0x7FFFFFFF
        $huge_size_alt = { FF FF FF FF } // 0xFFFFFFFF

    condition:
        uint16(0) == 0x4C58 or uint16(0) == 0x584C // "LX"
        and filesize < 1MB // typical for crafted PoC
        and ( any of ($lxf_magic*) )
        and ( any of ($huge_size*) )
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-25104 LXF File Upload Detection"; flow:established,to_server; http.request_body; content:"LXF"; nocase; content:"LECROY"; nocase; distance:0; pcre:"/Content-Type\s*:\s*(application\/octet-stream|application\/x-lxf|x-lxf)/iH"; classtype:attempted-admin; sid:202625104; rev:1; metadata:created_at 2026_05_15, updated_at 2026_05_15, cve CVE_2026_25104, severity high;)

# SMB and FTP variants
alert smb any any -> any any (msg:"CVE-2026-25104 LXF SMB Share"; content:"LXF"; nocase; classtype:attempted-admin; sid:202625105; rev:1;)

alert ftp any any -> any any (msg:"CVE-2026-25104 LXF FTP Upload"; content:"STOR"; nocase; content:".lxf"; nocase; classtype:attempted-admin; sid:202625106; rev:1;)

Elastic Detection

// Detect crashes from media parsing processes
sequence by process.entity_id with maxspan=1m
  [process where event.type == "start" and 
     (process.name == "mediainfo.exe" or process.name == "ffmpeg.exe" or process.name == "Plex Media Server.exe") and 
     process.args : ("*.lxf", "*.LXR", "*.Lecroy")]
  [process where event.type == "end" and 
     process.exit_code : (1, 2, 3, 3221225477, 3221225725)] // SIGSEGV, heap errors

Splunk SPL Query

index=windows_xmlwineventlog earliest=-7d
| search (EventCode=1000 OR EventCode=1001)
| where Image IN ("*mediainfo*", "*ffmpeg*", "*plex*", "*jellyfin*")
| rex field=Message "Faulting application name: (?<proc_name>[^,]+)"
| where proc_name IN ("mediainfo.exe", "ffmpeg.exe", "Plex Media Server.exe", "jellyfin.exe")
| eval threat_score = case(
    match(Message, "(?i)heap") AND match(Message, "(?i)buffer"), 80,
    match(Message, "(?i)unhandled exception"), 50,
    true(), 10)
| where threat_score > 50
| table _time, host, proc_name, EventCode, Message, threat_score
| sort -_time

Wazuh OSSEC Rule

<group name="CVE_2026_25104,">
  <rule id="247363" level="12">
    <if_sid>57100</if_sid> <!-- Windows Event 1000 fallback -->
    <match>(mediainfo|ffmpeg|plex|jellyfin)</match>
    <match>heap|buffer|unhandled exception</match>
    <description>CVE-2026-25104: Possible heap overflow exploitation in MediaInfoLib LXF parsing</description>
    <group>attack.execution,t1203,cve_2026_25104,</group>
    <mitre>
      <id>T1203</id>
    </mitre>
  </rule>
  
  <rule id="247364" level="8">
    <if_sid>2510401</if_sid>
    <match>EventCode = 1000|EventCode = 1001</match>
    <description>CVE-2026-25104: LXF parsing application crash detected (low confidence)</description>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Status: UNPATCHED (confidence 0/4). No vendor patch exists at the time of writing. Because this vulnerability is unpatched, defenders must implement compensatory controls.

Immediate Mitigations (until patch is available)

1. Input validation/allow-listing: Reject .lxf and .lxr file extensions at mail gateways, web application firewalls, and upload portals. Since LXF is a highly niche format (LeCroy oscilloscope data), blocking its processing has minimal legitimate-business impact in most environments.
2. Isolation: Run media-parsing services inside a sandboxed container (Wine/Docker/VM) with no network egress, minimal host filesystem access, and a restricted service account.
3. File-size restrictions: Enforce a maximum upload size (e.g., < 10 MB) — crafted PoCs are typically small; legitimate LXF files are often large (MBs of waveform data), reducing this limitation's legitimate impact.
4. Memory-protection hardening: If deploying MediaInfoLib in a custom application, compile with Hardened Source (Fortify, /GS), AddressSpaceLayoutRandomization (ASLR), DataExecutionPrevention (DEP/NX), and StackCanary (for heap: enable SafeSEH and /GUARD:CF).
5. Monitoring integration: Deploy the detection rules above to alert on any LXF parsing attempts or media-parsing crashes.

Patch/Upgrade Steps (when available)

1. Monitor vendor (MediaArea — GitHub: MediaArea/MediaInfoLib) release feed and mailing lists for a security advisory referencing CVE-2026-25104.
2. When patched version is released, update to the specified fixed version. Rebuild all software that embeds MediaInfoLib (e.g., FFmpeg builds, Plex, Jellyfin) against the patched library.
3. Upstream Linux distributions (Debian, Ubuntu, CentOS) will issue library updates once the vendor releases a fix.

Long-Term Hardening

1. Reduce attack surface: Disable LXF parsing if not required for business use. MediaInfoLib can be compiled with configuration flags to exclude specific parsers.
2. Fuzzing and regression: Maintain an internal corpus of malformed media files (including LXF) and run continuous fuzzing against any code that processes untrusted input. Integrate the resulting crash corpora into your CI pipeline to catch regressions in updated versions.
3. Tiered processing: Route all media processing through an isolated microservice with no lateral access. Apply the principle of least privilege — the service account should have read-only access to upload directories and no credentials to other systems.
4. Vendor accountability: Work with MediaArea to request a CWE classification and a proper patch publication. Flag this CVE in any vulnerability-management dashboard for priority remediation once a fix lands.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-25104 (NVD Description: MediaArea MediaInfoLib LXF parsing heap-based buffer overflow)
2. MediaInfoLib Official Repository: https://github.com/MediaArea/MediaInfoLib (Monitor for patch release — no fix yet)
3. MITRE ATT&CK T1203 — Exploitation for Client Execution (file-based exploitation technique): https://attack.mitre.org/techniques/T1203/
4. MediaInfo Official Site: https://mediaarea.net/en/MediaInfo (Identify downstream affected products and update channels)
5. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog (No listing for CVE-2026-25104 at time of writing)

Threat actor campaign evidence: No publicly documented campaigns or exploit-in-the-wild activity attributed to CVE-2026-25104 at the time of writing. EPSS score of 0.00207 (10.9th percentile) indicates a very low probability of current exploitation in the wild; however, this percentile is expected to rise given the unpatched state and the security-tooling deployment surface of MediaInfoLib. Monitor the CISA KEV catalog and vendor advisories for escalation.