PT-2026-41909 · Mozilla+1 · Thunderbird+2

Lebr0Nli · CVE-2026-8955 · Published 2026-05-19 · Updated 2026-06-29

Positive Technologies (AI Summary)

CVSS v3.1

8.8

High

Base vector

AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions Firefox versions prior to 151 Firefox ESR versions prior to 140.11 Thunderbird versions prior to 151 Thunderbird versions prior to 140.11

Description A privilege escalation issue exists within the DOM: Workers component.

Fix

DoS

LPE

Improper Privilege Management

Weakness Enumeration

CWE-269

Related Identifiers

ALSA-2026:21378

ALSA-2026:21380

ALSA-2026:21381

ALSA-2026:21382

ALSA-2026:22325

ALSA-2026:22643

CVE-2026-8955

OESA-2026-2392

OESA-2026-2393

OESA-2026-2394

OESA-2026-2465

OPENSUSE-SU-2026:10813-1

OPENSUSE-SU-2026:10863-1

OPENSUSE-SU-2026:10864-1

OPENSUSE-SU-2026:21168-1

Affected Products

Firefox

Rocky Linux

Thunderbird

References · 194

• https://errata.rockylinux.org/RLSA-2026:21378 · Vendor Advisory
• https://linux.oracle.com/errata/ELSA-2026-22643.html · Vendor Advisory
• https://mozilla.org/en-US/security/advisories/mfsa2026-50 · Vendor Advisory
• https://errata.almalinux.org/9/ALSA-2026-21378.html · Vendor Advisory
• https://osv.dev/vulnerability/ALSA-2026:21380 · Vendor Advisory
• https://errata.almalinux.org/8/ALSA-2026-21382.html · Vendor Advisory
• https://linux.oracle.com/errata/ELSA-2026-21382.html · Vendor Advisory
• https://errata.almalinux.org/10/ALSA-2026-22325.html · Vendor Advisory
• https://osv.dev/vulnerability/ALSA-2026:21382 · Vendor Advisory
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-8955 · Security Note
• https://mozilla.org/security/advisories/mfsa2026-51/#CVE-2026-8955 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-8956 · Security Note
• https://mozilla.org/en-US/security/advisories/mfsa2026-46/#CVE-2026-8955 · Vendor Advisory
• https://mozilla.org/en-US/security/advisories/mfsa2026-48 · Vendor Advisory
• https://errata.almalinux.org/9/ALSA-2026-21381.html · Vendor Advisory