CVE-2026-125199: FFmpeg memory leak in VC-1 decoder

Summary

FFmpeg through 9.0.2 contains a memory leak vulnerability in vc1_decode_frame() in libavcodec/vc1dec.c that leaks slice buffers when init_get_bits8() fails. Attackers can supply crafted files with repeated oversized VC-1 slices exceeding the bit reader limit to exhaust memory of decoding applications.

cve.now Index

7Pcve.now Index 7 of 100 · methodology v3 · provisional

Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
Exposure?/25Unknown. No advisory context yet
Reach?/20Unknown. No tracked technology or package matched
Severity6.8/10CVSS 6.8
No patch0/5No signal

What would change the score

Would score about 62 if added to CISA KEV
Would score about 57 if CISA's SSVC rates exploitation active
Would score about 29 if advisories confirm default setups are exposed

How the score works · Rankings

What to do

Apply the patch listed under Evidence.

Timeline

Nov 9, 2026, 7:11 PM UTCCVE published
Nov 9, 2026, 7:15 PM UTCFirst seen by cve.now

Affected versions

FFmpeg FFmpeg
From 8.1 · through 9.0.2

Evidence 5

Corrections

None so far.

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Questions about CVE-2026-125199

Is CVE-2026-125199 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: cve.now feed data

Which versions are affected by CVE-2026-125199?

FFmpeg: from 8.1 through 9.0.2.Source: cve.now feed data

FFmpeg through 9.0.2 Memory Leak in VC-1 Decoder via vc1_decode_frame()