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🛡️ CVE-2026-66038 — ffmpeg

🟡 CVSS 6.5 — Medium ✅ No Known Exploit CWE-908 NVD
6.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

FFmpeg through 8.1.2, fixed in commit 8670835, contains an information disclosure vulnerability in the LCL/ZLIB video decoder that allows attackers to expose uninitialized heap memory by supplying a valid zlib stream that inflates to fewer bytes than the expected frame size. The zlib_decomp() function in lcldec.c treats short decompression as non-fatal and continues to the RGB24 conversion path, which copies a full frame's worth of rows from the allocation buffer using original frame dimensions, causing uninitialized heap contents including pointer-derived allocator bytes to be copied into the attacker-observable AVFrame output and potentially defeating ASLR in long-lived media processing services.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: Required — someone has to click, open or visit something.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

CVE-2026-66038 is classified as CWE-908: Use of Uninitialized Resource. A resource is read before being initialised, so its contents are whatever was left there.

Affected software

CVE-2026-66038 is recorded against 1 package.

  • ffmpeg (fixed in 8.1.2)

Timeline and source

Published on 24 July 2026 and last revised on 7 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

code.ffmpeg.org
code.ffmpeg.org
www.vulncheck.com

Other advisories for this package

ffmpeg has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-908: Use of Uninitialized Resource) in other software:

Details

Severity MEDIUM
CVSS Score 6.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CWE CWE-908
Public Exploit ✅ No
Source NVD
Published 2026-07-24
Updated 2026-08-20
Modified 2026-08-07

Affected Packages

Software From version Fixed in
ffmpeg — 8.1.2

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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