CVE-2026-52295

Executive Summary

CVE-2026-52295 describes a buffer overflow vulnerability in FFmpeg version 7.0 and later, located within the libavformat/iamf_writer.c component. An attacker can trigger this flaw to cause a denial of service (DoS) condition, likely by supplying a crafted media file or stream that is processed by the IAMF (Immersive Audio Model and Formats) writer module. Any organization that uses FFmpeg 7.0 or newer to process untrusted media input — including streaming platforms, media transcoding services, and applications embedding FFmpeg — is potentially affected. As of this writing, no patch, workaround, or vendor advisory has been published, and no public proof-of-concept exploit exists, leaving affected deployments exposed to availability disruption.

Technical Analysis

The vulnerability resides in the libavformat/iamf_writer.c component of FFmpeg, a library responsible for writing IAMF (Immersive Audio Model and Formats) container data. The NVD description identifies this as a buffer overflow condition in FFmpeg v.7.0 and later.

Vulnerability Mechanism: A buffer overflow occurs when a program writes data beyond the boundaries of an allocated memory buffer. In the context of the IAMF writer, this typically happens during the serialization of metadata structures into the output container. The writer likely fails to perform adequate bounds checking when copying variable-length fields (e.g., string metadata, parameter blocks, or sample data) into fixed-size stack or heap buffers. When malformed or excessively large input values are provided to the writer — for example, via a crafted media packet with oversized metadata descriptors — the unchecked write corrupts adjacent memory.

Attack Surface: The attack surface is the FFmpeg library as a whole, specifically any code path that invokes the IAMF writer. This includes:

• CLI usage: ffmpeg -i input.mov output.iamf
• Library API usage: applications calling avformat_write_header(), av_write_frame(), or related functions with an IAMF output format context.
• Transcoding pipelines that convert audio streams to the IAMF format for immersive audio delivery.

Code-Level Considerations: Because the NVD description is sparse, the exact function names and vulnerable code paths within libavformat/iamf_writer.c are not confirmed. However, the buffer overflow class implies a missing or inadequate bounds check on a memory copy operation (e.g., memcpy, avio_write, or an assignment loop). An attacker who can influence the size or content of fields written by this module can overflow the buffer.

Trigger Conditions: The overflow is likely triggered by feeding FFmpeg a specially crafted input file or stream that is then transcoded/written to IAMF output. Since the vulnerability is in the writer (output) path rather than the demuxer, the attacker must either:

1. Provide a malicious input file designed to produce oversized metadata when written to the IAMF container, or
2. Exploit a chained vulnerability in an input parser to inject oversized values that propagate to the writer.

Impact of the Flaw: The overflow corrupts adjacent memory, which can cause an out-of-bounds read/write, a segmentation fault, or an assertion failure — all resulting in process termination (DoS). In rare cases, advanced exploitation could lead to arbitrary code execution, but the NVD description specifically states denial of service, and reliable code execution from this class of bug typically requires detailed reverse engineering of the corrupted memory layout.

Exploitation Scenarios

No public PoC exists for CVE-2026-52295; the attack chain below is inferred from the vulnerability class and the component identified. The attack progression would proceed as follows:

Step 1: Reconnaissance and Target Identification An attacker identifies systems that process media with FFmpeg 7.0+ and produce IAMF output. This includes:

• Media transcoding services (cloud or on-premise)
• Content delivery pipelines that convert audio to immersive formats
• Desktop applications embedding FFmpeg for media conversion
• Automated ingestion systems where users can upload media files

The attacker enumerates these targets by scanning for exposed FFmpeg-based web services, API endpoints accepting media uploads, or misconfigured transcode servers.

Step 2: Crafting the Malicious Input The attacker creates a media file (e.g., a crafted MOV, MP4, WAV, or raw audio stream) whose structure is designed to trigger the buffer overflow when FFmpeg writes it as IAMF. Specifically, the input must cause the IAMF writer to copy an oversized payload into a fixed-size buffer. This is achieved by embedding oversized values in metadata fields that the writer serializes without proper validation — for example, overly long descriptive strings, excessive parameter block counts, or malformed audio element descriptors.

Step 3: Delivery and Executing the Flaw The attacker delivers the crafted file to the target:

• Direct upload: If the target exposes a web UI or API that accepts media files, the attacker uploads the malicious file. The server processes it with FFmpeg, which converts it to IAMF and triggers the overflow.
• Indirect delivery: For offline or locally processed systems, the attacker may use social engineering to get a user to open/process the file (e.g., emailed attachment, shared via collaboration tools).
• Streaming: If the target accepts network streams (e.g., RTSP, HLS) and re-encodes them, the attacker could inject the malicious payload into a live stream.

During processing, the vulnerable copy operation in libavformat/iamf_writer.c overruns the destination buffer, corrupting the stack or heap.

Step 4: Post-Exploitation Impact The immediate result is a crash of the FFmpeg process. In a batch transcode pipeline, one crash may cause the entire job to fail, forcing a restart. In a continuous service, repeated submissions of the crafted file cause repeated crashes, leading to:

• Denial of service of the media processing API
• Resource exhaustion from repeated process restarts
• Cascading failures in downstream consumers that wait for transcoded output
• Potential data loss if the crash occurs mid-write of a partially processed file

If the attacker succeeds in corrupting memory in a controlled manner (unlikely without a PoC), code execution might be achievable, but this is speculative at present.

Impact Assessment

Confidentiality Impact: None directly — this is an availability-focused vulnerability. However, if memory corruption is leveraged for code execution (currently unproven), confidentiality could be compromised.

Integrity Impact: Low. The buffer overflow corrupts memory contents, potentially leading to inconsistent output files, but there is no evidence of data manipulation control.

Availability Impact: High. The primary and documented impact is denial of service. A remote attacker can crash the FFmpeg process repeatedly, degrading or disabling media processing capabilities.

Affected Systems: All deployments using FFmpeg version 7.0 or later that write IAMF output. This includes:

• On-demand video/audio transcode services
• Streaming origin servers
• Embedded systems (e.g., set-top boxes, IoT media players)
• Content management systems with media conversion features
• Developer libraries and SDKs wrapping FFmpeg

Blast Radius: The vulnerability requires the attacker to supply input that reaches the IAMF writer. Systems that only decode media (never write IAMF) are not exposed unless they can be coerced into writing IAMF output. The remote attack surface is moderate — the attacker needs a valid delivery channel for the malicious input.

CVSS Considerations: No CVSS score has been assigned (N/A). Based on the vulnerability class, an estimated score would prioritize availability (e.g., CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H ≈ 6.5), but this is an unofficial inference and should not replace a formal score from the CNA.

Detection Guidance

The following detection rules target anomalous media processing behavior, crashes, and malformed IAMF output attempts. They are heuristic because no known exploit signature exists.

Sigma Rule

title: FFmpeg IAMF Writer Buffer Overflow Attempt
id: 7e3e6004-2b1e-4f9a-9c3d-8b7e0f2a4c55
status: experimental
description: Detects FFmpeg process crashes or abnormal termination patterns associated with the IAMF writer component (libavformat/iamf_writer.c)
author: Valtersit Threat Intelligence
date: 2026/05/15
logsource:
  category: process_creation
  product: linux
detection:
  selection_ffmpeg:
    Image|endswith:
      - '/ffmpeg'
      - 'ffmpeg.exe'
  selection_args:
    CommandLine|contains:
      - 'iamf'
      - '-f iamf'
      - 'output.iamf'
  condition: selection_ffmpeg and selection_args
  timeframe: 5m
falsepositives:
  - Legitimate IAMF encoding operations
level: medium

YARA Rule

rule FFmpeg_IAMF_Writer_Overflow_Indicators
{
    meta:
        author = "Valtersit Threat Intelligence"
        description = "Detects patterns in files or memory associated with CVE-2026-52295 IAMF writer buffer overflow"
        date = "2026-05-15"
        severity = "high"
        reference = "CVE-2026-52295"

    strings:
        // IAMF container signature (ISOBMFF box 'iamf')
        $iamf_magic = { 69 61 6D 66 } // "iamf" ascii

        // FFmpeg IAMF writer source references
        $writer_ref = "iamf_writer.c" ascii
        $writer_ref2 = "iamf_writer" ascii

        // Common oversized metadata pattern (very long strings)
        $long_meta = "metadata" ascii fullword

    condition:
        uint32(0) == 0x6672616D or // "fram"
        $iamf_magic at 0 and
        (uint32(4) == 0x6672616D or uint32(4) == 0x6D6F6F76) and // "fram" or "moov"
        (#long_meta > 100) or
        any of ($writer_ref*)
}

Suricata IDS Rule

alert ip any any -> any any (msg:"CVE-2026-52295 Potential FFmpeg IAMF Writer Buffer Overflow - Malformed IAMF Container"; flow:established,to_server; content:"iamf"; fast_pattern; content:"|00 00 00 00|"; within:20; metadata:created_at 2026_05_15, updated_at 2026_05_15; reference:cve,2026-52295; classtype:attempted-dos; sid:2009999; rev:1;)

Note: Due to the absence of known exploit payloads, this rule detects IAMF container traffic containing suspiciously large or malformed box structures. Adjust thresholds based on legitimate IAMF traffic in your environment.

Elastic Detection

// EQL query for FFmpeg process crashes or abnormal exit codes
sequence by process.entity_id
  [ process where process.name == "ffmpeg" and
    (process.args contains "iamf" or process.args contains "-f iamf") ]
  [ file where file.extension == "core" and file.path contains "ffmpeg" ]

Alternative EQL for high-volume crash correlation:

// Repeated FFmpeg crashes within short timeframe
any where process.name == "ffmpeg"
  and (process.exit_code >= 128 or process.args contains "iamf")
  | stats crash_count = count() by process.name, agent.id
  | where crash_count > 5

Splunk SPL Query

index=windows OR index=linux sourcetype=WinEventLog:Security OR sourcetype=syslog
| search "ffmpeg" AND ("segmentation" OR "crash" OR "core dumped" OR "SIGSEGV" OR "SIGABRT")
| stats count by host, user, dest, _time
| eval severity=if(count > 5, "high", "medium")
| where severity="high"

For application-level logs:

index=app_logs
| search "ffmpeg" AND ("iamf" OR "iamf_writer" OR "Buffer overflow" OR "AVERROR" OR "Aborted")
| bin _time span=1m
| stats count by host, _time
| where count > 10
| sort - count

Wazuh OSSEC Rule

<group name="ffmpeg,">
    <rule id="100300" level="10">
        <if_sid>5715</if_sid>  <!-- Trigger on process crash events -->
        <match>ffmpeg</match>
        <regex>Segmentation fault|core dumped|SIGSEGV|SIGABRT|Aborted</regex>
        <description>FFmpeg process crash - potential CVE-2026-52295 IAMF writer buffer overflow</description>
        <group>ffmpeg_crash,</group>
        <mitre>
            <id>T1499</id>
        </mitre>
    </rule>

    <rule id="100301" level="7">
        <if_sid>100300</if_sid>
        <same_field>host</same_field>
        <field name="host">\.</field>
        <regex>iamf</regex>
        <description>FFmpeg crash involving IAMF output - high confidence CVE-2026-52295 exploitation</description>
        <group>ffmpeg_crash,</group>
        <mitre>
            <id>T1499</id>
        </mitre>
    </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 0/4 — UNPATCHED. No upstream fix has been published by the FFmpeg project as of this report. There is no vendor advisory, no CVE-linked patch commit, and no workaround documentation.

Immediate Mitigations (until patch is available):

1. Restrict IAMF output usage: If IAMF encoding is not a business requirement, disable or remove support for the IAMF muxer. Compile FFmpeg with --disable-muxer=iamf or filter it out at runtime by blocking output format requests for IAMF.
2. Input sanitization: Validate all input files before processing. Reject files with unusual metadata sizes, excessive box counts, or anomalous container structures. Use a pre-processing stage (e.g., ffprobe) to inspect files and flag suspicious characteristics.
3. Network isolation: Place FFmpeg processing services on internal networks with strict access control lists. Prevent untrusted users from directly submitting files to the transcode pipeline.
4. Resource limits: Run FFmpeg under cgroups or container resource limits (memory, CPU) to contain blast radius if a crash occurs. Use ulimit to restrict memory allocation.
5. Rate limiting and monitoring: Implement rate limiting on media upload/transcode endpoints. Monitor crash rates; repeated crashes (5+ within a short window) should trigger alerts and auto-blocking of the submitter.
6. Process monitoring: Use supervisors (systemd, Docker restart policies) to automatically restart crashed FFmpeg processes, maintaining service availability while reducing opportunities for sustained DoS.

Patch/Upgrade Steps:

1. Monitor the FFmpeg Git repository and security advisories for commits referencing libavformat/iamf_writer.c or CVE-2026-52295.
2. Subscribe to the FFmpeg-devel mailing list and NVD alerts for CVE-2026-52295.
3. When a fix is released, upgrade to the patched version immediately. In the interim, consider downgrading to FFmpeg 6.x if IAMF output is non-critical (note: this may not preserve all features).

Long-Term Hardening:

1. Code review: Contribute to or request a security audit of the IAMF writer component, focusing on bounds checking and use of safe string/array copy functions (av_strlcpy, av_memcpy_backptr, etc.).
2. Fuzzing: Implement continuous fuzzing for the IAMF muxer (e.g., with AFL++ or libFuzzer targeting avformat_write_header). Integrate into CI/CD.
3. Memory safety: Evaluate compiling FFmpeg with memory sanitizers (ASan/UBSan) in test environments to catch similar overflow classes earlier.
4. Defense in depth: Isolate FFmpeg processing in microservices with minimal privileges; restrict the host paths and files the process can write to.
5. Adversarial testing: Consider regression testing with malformed media corpus (e.g., from OSS-Fuzz) to proactively identify similar writer-path overflows.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-52295 (Contains the official CVE description and any future updates)
2. FFmpeg Official Site: https://ffmpeg.org/ (Monitor for release notes and security advisories)
3. FFmpeg Git Repository: https://git.ffmpeg.org/ffmpeg.git (Watch for patches to libavformat/iamf_writer.c)
4. CWE-121 (Stack-based Buffer Overflow): https://cwe.mitre.org/data/definitions/121.html (Reference for vulnerability class)
5. MITRE ATT&CK T1499 — Endpoint Denial of Service: https://attack.mitre.org/techniques/T1499/ (Tactics and techniques reference)

Threat Actor Campaigns: None identified at this time. No exploit-in-the-wild evidence, exploit code, or active campaign has been reported. CISA KEV status: NO. EPSS: Not scored. This vulnerability is currently a latent risk awaiting either public exploit development or a vendor patch.