CVE-2026-6751Network attack vector

Information disclosure via incorrect video frame stride

Published Apr 21, 2026 · Updated Jul 15, 2026

Uninitialized memory in Mozilla Firefox 149 Web Codecs allows remote attackers to read decoder padding via video frame copying. VideoFrame.cpp uses a width-derived stride instead of the image's actual stride, causing Resource::CopyTo to expose padding bytes to JavaScript. Affected Firefox and Thunderbird packages on Red Hat Enterprise Linux 7, 8, 9, and 10 require script execution and padded YUV decoder output; the disclosed behavior reads decoder-buffer data rather than demonstrating code execution.

CVSS severity7.5
High
EPSS probability0.46%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uninitialized memory in Mozilla Firefox 149 Web Codecs allows remote attackers to read decoder padding via video frame copying. VideoFrame.cpp uses a width-derived stride instead of the image's actual stride, causing Resource::CopyTo to expose padding bytes to JavaScript. Affected Firefox and Thunderbird packages on Red Hat Enterprise Linux 7, 8, 9, and 10 require script execution and padded YUV decoder output; the disclosed behavior reads decoder-buffer data rather than demonstrating code execution.

The record

CVE
CVE-2026-6751
Published
Apr 21, 2026
Updated
Jul 15, 2026
Vendor
libuser Project
Product
Red Hat Enterprise Linux 9
Classifications
CWE-457, CWE-824
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 15, 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?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

libuser Project · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 7Affected versions are unavailable in this record.

Published CVSS scores

7.3UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
6.3Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
7.5Red HatCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
7.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-457Use of Uninitialized Variable
CWE-824Access of Uninitialized Pointer

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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