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NVD / CVE Program· CNA VulnCheck

CVE-2026-125233: FFmpeg through 9.0.2 Heap Buffer Overflow via DVB Subtitle Encoder

Noroxi assessment

Priority: Monitor (action score 34/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.14% (FIRST EPSS).
  • Someone with local access to the system can trigger it. No account or password is required. No special conditions are required; it is repeatable.
  • No fixed version is recorded, but the references include a patch (commit or PR) link.

Low priority for now. See the fix and affected versions sections below.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

FFmpeg through 9.0.2 contains a heap buffer overflow vulnerability in dvbsub_encode() in libavcodec/dvbsubenc.c that undercounts each CLUT segment header by two bytes. Attackers can supply a file with many bitmap subtitle rectangles that, when transcoded to the dvbsub encoder, writes past the output buffer and corrupts heap memory.

HighCVSS 8.5 · v4.0—No exploit No fix recorded
Published
Nov 9, 2026
Updated
Nov 10, 2026
EPSS
0.1% · 3th percentile

Report tools

JSON

Action score

34

Monitor

Low priority for now.

CVSS
34 / 40 · 8.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
—
CNA · VulnCheck
8.5
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-125233

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • FFmpeg FFmpeg

    • up to and including 9.0.2affected · semver

Same product

ffmpeg: all records

Other highest-scoring records for the same primary product.

  • CVE-2009-4637FFmpeg 0.5 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via unknown vectors that…
    45Plan
  • CVE-2016-10190Heap-based buffer overflow in libavformat/http.c in FFmpeg before 2.8.10, 3.0.x before 3.0.5, 3.1.x before 3.1.6, and 3.2.x before 3.2.2…
    42Plan
  • CVE-2009-4634Multiple integer underflows in FFmpeg 0.5 allow remote attackers to cause a denial of service and possibly execute arbitrary code via a…
    42Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-125231Nov 9, 2026 · FFmpeg 4.4 through 9.0.2 NULL Pointer Dereference via adx_decode_header()
    27Monitor
  • ← EarlierCVE-2026-125232Nov 9, 2026 · FFmpeg through 9.0.2 Division by Zero in B-frame Motion Estimation
    27Monitor
  • Later →CVE-2026-125234Nov 9, 2026 · FFmpeg through 9.0.2 WavPack Encoder Integer Overflow Infinite Loop via wavpack_encode_init
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-1252090 days apartFFmpeg before 8.1.3 and 9.x before 9.0.2 Heap Buffer Overflow via dvdsubenc.c
    34Monitor
  • CVE-2026-65706109 days apartFFmpeg 3.0 - 8.1.2 vf_swaprect Out-of-Bounds Write via NV12 Frame Processing
    34Monitor
  • CVE-2026-1252100 days apartFFmpeg through 9.0.2 Heap Overflow in libaribcaption Text Subtitle Decoding
    29Monitor
  • CVE-2026-65705109 days apartFFmpeg 3.4 - 8.1.2 vf_floodfill Out-of-Bounds Write via filter_frame()
    29Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
P
Scope
X

Weakness class (CWE)

CWE-131 · Incorrect Calculation of Buffer Size

CVSS vector

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Exploit maturity— → none

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References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records