FFmpeg before 8.1.3 and 9.x before 9.0.2 Heap Buffer Overflow via dvdsubenc.c
Only FFmpeg builds before 8.1.3 and 9.x before 9.0.2 are affected, and only when bitmap subtitles are transcoded to the dvdsub encoder with odd-width rectangles. Fixed in 8.1.3 and 9.0.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 8.1.3, 9.0.2
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. FFmpeg before 8.1.3, or 9.x before 9.0.2 The input contains a rectangle with odd width, which the DVD subtitle encoder's RLE size estimate underestimates Bitmap subtitles are transcoded to the dvdsub encoder
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 14/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
FFmpeg before 8.1.3 and 9.x before 9.0.2 contains a heap buffer overflow vulnerability in the DVD subtitle encoder that underestimates RLE output size for odd-width rectangles. Attackers can supply files with crafted bitmap subtitles that, when transcoded to the dvdsub encoder, write past the output buffer and corrupt heap memory.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure5/25Specific setups only
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.5/10CVSS 8.5
- No patch0/5No signal
What would change the score
- Would score about 64 if added to CISA KEV
- Would score about 59 if CISA's SSVC rates exploitation active
- Would score about 24 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
FFmpeg before 8.1.3, or 9.x before 9.0.2 The input contains a rectangle with odd width, which the DVD subtitle encoder's RLE size estimate underestimates Bitmap subtitles are transcoded to the dvdsub encoderUpgrade to a fixed version: 8.1.3, 9.0.2.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- FFmpeg FFmpeg
fixed in 8.1.3; From 9.0 · fixed in 9.0.2
Evidence 5
- Patch
- Report
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-125209
Is CVE-2026-125209 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
What does this mean?
The DVD subtitle encoder underestimates the size of its RLE output for subtitle rectangles with odd width. The encoder then writes past the end of its output buffer, corrupting heap memory.Source: vulncheck.com
Which versions are affected by CVE-2026-125209?
FFmpeg: before 8.1.3; from 9.0 before 9.0.2.Source: cve.now feed data
Am I affected, and how do I check?
FFmpeg versions before 8.1.3 and 9.x versions before 9.0.2 are in scope. The bug needs bitmap subtitles transcoded to the dvdsub encoder, with an input rectangle of odd width. Check your version with ffmpeg -version.Source: vulncheck.com
How do I fix CVE-2026-125209?
Upgrade to FFmpeg 8.1.3 or 9.0.2, depending on which release line you use.Source: vulncheck.com