EUVD-2026-74264
GHSA-crqp-42h3-7fcv
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessCraft malicious H.264/HEVC file
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DeliveryDeliver file to FFmpeg-based pipeline or user
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ExploitUser/process invokes FFmpeg RTP encoding
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ExecutionNegative size passed to memcpy in nal_send()
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PersistHeap out-of-bounds write triggered
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ImpactArbitrary code execution in FFmpeg process context
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, write limits
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires the target to process a crafted H.264 or HEVC media file using FFmpeg's RTP encoding path (libavformat/rtpenc_h264_hevc.c). The code path is triggered when FFmpeg is used to packetize H.264/HEVC video for RTP output - this is a common but not universal deployment pattern (e.g., live-streaming pipelines, RTSP servers built on FFmpeg). User interaction is required per CVSS UI:R: a human or automated job must actively invoke FFmpeg against the crafted input. No authentication or elevated privileges are required from the attacker's side (PR:N). Limiting factors: (1) victim must use FFmpeg's RTP output mode with H.264 or HEVC codec; (2) a user or process must initiate the encoding of attacker-controlled input; (3) exploitation does not extend beyond the scope of the FFmpeg process (S:U). |
| Impact | The CVSS 8.8 score (AV:N/AC:L/PR:N/UI:R) appropriately reflects that exploitation requires a victim to process a crafted file, which is a realistic user-interaction barrier since FFmpeg is commonly invoked on user-supplied or remotely fetched media. Despite the high CVSS score, the EPSS score of 0.17% (6th percentile) indicates that the security research community currently assesses low near-term exploitation probability, even given the public PoC hosted on GitHub. No CISA KEV listing confirms that mass exploitation has not been observed. The public PoC and the precision of the crash address (-3 size) suggest the bug is deterministic and reproducible once triggered, lowering the effective attack complexity for a motivated attacker beyond what AC:L alone conveys. The S:U scope rating limits blast radius to the FFmpeg process itself, though in server-side transcoding pipelines FFmpeg commonly runs with service-level credentials, making process compromise still impactful. |
| Exploit ScenarioDerived | An attacker crafts a malicious H.264 or HEVC media container with a NAL unit structure that causes FFmpeg's nal_send() to compute a negative size value. The file is delivered to a victim - for example, via a media-sharing link, a malicious upload endpoint, or a live RTP stream - and the victim's FFmpeg instance processes it for transcoding or re-streaming. Heap corruption from the out-of-bounds memcpy write can be leveraged for arbitrary code execution within the FFmpeg process. A public PoC is available at https://github.com/momo-trip/poc_ffmpeg demonstrating the crash. |
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Alert meAnalysisAIv1 – Sep 09, 2026
Memory corruption in FFmpeg before 8.1 allows an attacker who can supply a crafted H.264/HEVC media file to corrupt heap memory during RTP encoding, with potential for arbitrary code execution. The root cause is in nal_send() within libavformat/rtpenc_h264_hevc.c, where a negative size value (-3) is passed directly to memcpy, producing an out-of-bounds write. A public proof-of-concept exploit is available, though EPSS probability remains low at 0.17% and no active exploitation has been confirmed by CISA.
RemediationAI
Upgrade to FFmpeg 8.1 or later, which includes the fix landed in upstream pull request #20746 (https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20746). Distributions packaging FFmpeg should apply this patch or backport the fix to their supported branch. As a compensating control where upgrading is not immediately feasible, operators can restrict processing of untrusted media files by sandboxing FFmpeg invocations (e.g., via seccomp/AppArmor/namespaces on Linux), which limits the impact of heap corruption to the sandboxed process. Disabling RTP output encoding for H.264/HEVC specifically (if not operationally required) removes the vulnerable code path entirely. Note that sandboxing adds deployment complexity and may interfere with FFmpeg's access to hardware accelerators.
Affected VersionsENISA
Affects your stack
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Technical ContextAI · show details
FFmpeg is an open-source multimedia framework whose libavformat library handles container muxing and demuxing, including RTP packetization of H.264 and HEVC video. The nal_send() function in rtpenc_h264_hevc.c is responsible for fragmenting NAL units for RTP transmission. The bug is a CWE-787 (out-of-bounds write): a size variable computed from crafted input can underflow to a negative integer (-3), which when cast to the size_t parameter of memcpy becomes a very large unsigned value, triggering a heap memory corruption write. The defect was surfaced via AddressSanitizer instrumentation. The EUVD CPE entry lists 'n/a n/a', which is a placeholder - the actual affected codebase is FFmpeg proper, all versions before 8.1.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Crafted file deliverable over network with no auth; user must invoke encoding (UI:R); heap corruption enables full process compromise (C:H/I:H/A:H); scope unchanged.
Primary rating from Vendor (mitre).
CVSS VectorVendor: mitre
Lifecycle Timeline
3DescriptionCVE.org
A memory corruption vulnerability exists in FFmpeg before 8.1. The RTP encoding process. In the nal_send function in libavformat/rtpenc_h264_hevc.c, a negative size parameter (size=-3) is passed to memcpy when transmitting H.264/HEVC streams via RTP using a crafted input file. This was detected using AddressSanitizer.
Technical POC Analysis
The bug is a missing sign check on a NAL-unit length before it is used as a memcpy length, producing an out-of-bounds write in the RTP H.264/HEVC muxer.
Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.
Latest POC
1 PoC candidate from github (unverified)
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Executive ViewAI
FFmpeg versions before 8.1 are vulnerable to memory corruption in H.264/HEVC encoding that could enable arbitrary code execution when processing malicious video files. This poses a critical risk to organizations using FFmpeg for media streaming, transcoding, or video processing, with public exploit code available and no vendor patch currently deployed.
No vendor-released patch identified at time of analysis. Until FFmpeg can be upgraded to version 8.1 or later, restrict media file sources to internal or explicitly whitelisted external sources; isolate FFmpeg processes in containers with enforced resource limits and no network access; implement strict input validation and file type verification on all media inputs; deploy monitoring and alerting for anomalous FFmpeg process behavior; establish quarterly audits of third-party media processing dependencies; consider migrating critical workflows to patched alternative video processing libraries.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.
FFmpeg 2.x allows remote attackers to conduct cross-origin attacks and read arbitrary files by using the concat protocol
FFmpeg before 2.8.12, 3.0.x and 3.1.x before 3.1.9, 3.2.x before 3.2.6, and 3.3.x before 3.3.2 does not properly restric
FFmpeg 2.x allows remote attackers to conduct cross-origin attacks and read arbitrary files by using the subfile protoco
The av_reallocp_array function in libavutil/mem.c in FFmpeg before 2.0.1 has an unspecified impact and remote vectors re
cbs_jpeg_split_fragment in libavcodec/cbs_jpeg.c in FFmpeg 4.1 and 4.2.2 has a heap-based buffer overflow during JPEG_MA
Out-of-bounds heap write in FFmpeg's RASC video decoder (decode_dlta in libavcodec/rasc.c) allows attackers to corrupt m
Integer Overflow vulnerability in function filter_sobel in libavfilter/vf_convolution.c in Ffmpeg 4.2.1, allows attacker
Integer Overflow vulnerability in function filter_robert in libavfilter/vf_convolution.c in Ffmpeg 4.2.1, allows attacke
Integer Overflow vulnerability in function filter_prewitt in libavfilter/vf_convolution.c in Ffmpeg 4.2.1, allows attack
Integer Overflow vulnerability in function filter16_sobel in libavfilter/vf_convolution.c in Ffmpeg 4.2.1, allows attack
Integer Overflow vulnerability in function filter16_roberts in libavfilter/vf_convolution.c in Ffmpeg 4.2.1, allows atta
FFmpeg <=4.3 contains a buffer overflow vulnerability in libavcodec through a crafted file that may lead to remote code
Exploit-DB