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CVE-2026-120246— FFmpeg 4.4 through 9.0.2 Uninitialized Memory Disclosure via CDXL HAM Decoder

Quick assessment

Affected
FFmpeg FFmpeg
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

FFmpeg 4.4 至 9.0.2 版本在 CDXL 解码器中存在一个未初始化变量使用漏洞。该漏洞会通过未填充的 HAM 调色板条目，将栈内存泄露到解码后的像素数据中。攻击者可构造一个类型为 0 的 CDXL 文件，使其 HAM 像素在 或 函数中选择未填充的 条目，从而在 BGR24 输出中暴露栈字节和指针片段。

CVSS 5.5 · Medium

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
FFmpeg FFmpeg 4.4≤ 9.0.2 affected
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I. Basic Information for CVE-2026-120246

Vulnerability Information
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Vulnerability Title
FFmpeg 4.4 through 9.0.2 Uninitialized Memory Disclosure via CDXL HAM Decoder
Source: CVE Program / CVE List V5
Vulnerability Description
FFmpeg 4.4 through 9.0.2 contains a use of uninitialized variable vulnerability in the CDXL decoder that leaks stack memory into decoded pixels via unfilled HAM palette entries. Attackers can craft a type-0 CDXL file whose HAM pixels select unfilled new_palette entries in cdxl_decode_ham8() or cdxl_decode_ham6(), exposing stack bytes and pointer fragments in the BGR24 output.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用未经初始化的变量
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
FFmpeg FFmpeg 4.4 ~ 9.0.2 -

II. Public POCs for CVE-2026-120246

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-120246

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Other References for CVE-2026-120246 (4)

Same Patch Batch · FFmpeg · 2026-11-01 · 5 CVEs total

CVE-2026-120247 5.5 MEDIUM FFmpeg 2.3 through 9.0.2 Huffyuv Decoder Uninitialized Heap Memory Disclosure
CVE-2026-120244 5.5 MEDIUM FFmpeg 2.1 through 9.0.2 Uninitialized Memory Leak via PCX Decoder
CVE-2026-120243 5.5 MEDIUM FFmpeg 2.0 through 9.0.2 Information Disclosure via G2M Kempf Palette
CVE-2026-120245 5.5 MEDIUM FFmpeg 0.10 through 9.0.2 Uninitialized Memory Disclosure via Sun Raster Decoder

IV. Related Vulnerabilities

Same product: FFmpeg
Same vendor: FFmpeg
Same weakness: CWE-457