CVE-2026-70631

Heap-memory disclosure via short Deflate strip

Published Aug 6, 2026 · Updated Aug 6, 2026

Uninitialized memory use in FFmpeg 0.5 through versions before 9.0 allows attackers to expose stale heap data through crafted TIFF decoding. In tiff_unpack_zlib(), a short but successful Deflate strip leaves part of the allocated strip buffer unwritten, yet row copies consume the full declared size and place stale heap bytes in decoded output. Successful exposure requires attackers to cause a vulnerable process to decode the file and then obtain its output; persistent services can disclose data left by earlier allocations.

CVSS severity6.8
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uninitialized memory use in FFmpeg 0.5 through versions before 9.0 allows attackers to expose stale heap data through crafted TIFF decoding. In tiff_unpack_zlib(), a short but successful Deflate strip leaves part of the allocated strip buffer unwritten, yet row copies consume the full declared size and place stale heap bytes in decoded output. Successful exposure requires attackers to cause a vulnerable process to decode the file and then obtain its output; persistent services can disclose data left by earlier allocations.

The record

CVE
CVE-2026-70631
Published
Aug 6, 2026
Updated
Aug 6, 2026
Vendor
FFmpeg
Product
FFmpeg
Classifications
CWE-908, T1005
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 2026Record 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=0.5 <9.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

FFmpeg · FFmpegversion=0.5 <9.0

Published CVSS scores

5.5VulnCheck CNACVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
6.8VulnCheck CNACVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource
T1005Data from Local System

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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