CVE-2026-6746Public exploitNetwork attack vector

Content-process crash via cross-root slot reassignment

Published Apr 21, 2026 · Updated Jul 15, 2026

Use-after-free in Mozilla Firefox DOM before 150 allows remote attackers to crash a content process via crafted HTML. HTMLSlotElement::Assign assumes the previous assigned slot belongs to the new slot's shadow root and mishandles cross-root manual reassignment, causing a layout use-after-free. Exposure requires processing scripted HTML; Thunderbird's normal mail reader disables scripting, and the public reproducer demonstrates a crash rather than code execution.

CVSS severity7.5
High
EPSS probability0.58%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Mozilla Firefox DOM before 150 allows remote attackers to crash a content process via crafted HTML. HTMLSlotElement::Assign assumes the previous assigned slot belongs to the new slot's shadow root and mishandles cross-root manual reassignment, causing a layout use-after-free. Exposure requires processing scripted HTML; Thunderbird's normal mail reader disables scripting, and the public reproducer demonstrates a crash rather than code execution.

The record

CVE
CVE-2026-6746
Published
Apr 21, 2026
Updated
Jul 15, 2026
Vendor
libuser Project
Product
Red Hat Enterprise Linux 9.6 Extended Update Support
Classifications
CWE-825, CWE-416, T1499.004
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

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 9.6 Extended Update SupportAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 9.0 Update Services for SAP SolutionsAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 9.2 Update Services for SAP SolutionsAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 8.6 Telecommunications Update ServiceAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 10.0 Extended Update SupportAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 7 Extended Lifecycle SupportAffected 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 8.6 Update Services for SAP SolutionsAffected 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 8.8 Telecommunications Update ServiceAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 9.4 Extended Update SupportAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 8.8 Update Services for SAP SolutionsAffected versions are unavailable in this record.
libuser Project · Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-OnAffected versions are unavailable in this record.

Published CVSS scores

7.5Red HatCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5OracleCVSS:3.1/AV:N/AC:H/PR:N/UI:R/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.

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 exploitPublished

Weakness, pattern, technique

CWE-825Expired Pointer Dereference
CWE-416Use After Free
T1499.004Application or System Exploitation

Public exploit references

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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