CVE-2023-51791

Local code execution via oversized ANS alphabet

Published Apr 19, 2024 · Updated Nov 4, 2025

Out-of-bounds read in FFmpeg N113007-g8d24a28d06 allows local users to execute arbitrary code through a crafted JPEG XL stream. The JPEG XL parser accepts an ANS cluster alphabet larger than its bundle table, causing gen_alias_map to access beyond a stack variable. Exploitation requires local access to make an affected process parse the stream and grants code execution in that process.

CVSS severity7.8
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in FFmpeg N113007-g8d24a28d06 allows local users to execute arbitrary code through a crafted JPEG XL stream. The JPEG XL parser accepts an ANS cluster alphabet larger than its bundle table, causing gen_alias_map to access beyond a stack variable. Exploitation requires local access to make an affected process parse the stream and grants code execution in that process.

The record

CVE
CVE-2023-51791
Published
Apr 19, 2024
Updated
Nov 4, 2025
Vendor
FFmpeg
Product
FFmpeg
Classifications
CWE-125, T1203
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 19, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=-

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

FFmpeg · FFmpegversion=-

Published CVSS scores

7.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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