CVE-2026-8955

Description

Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

Overview

State: PUBLISHED
Assigner (CNA): mozilla
CVSS severity: high
CVSS score: 8.8 / 10
CVSS vector: AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Effective score: 8.8 / 10 HIGH source: CNA overview
CWE(s): —
Reserved: 2026-05-19
Published: 2026-05-19 12:29 UTC
Last updated: 2026-05-20 15:37 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/8xxx/CVE-2026-8955.json
Linked Threat: CVE-2026-8955 — CVE-2026-8955

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-05-19 14:16:51 UTC
NVD last modified: 2026-05-20 17:16:29 UTC
NVD CVSS v3.1: 8.8 / 10 HIGH source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Exploitability subscore: 2.8 / 10
Impact subscore: 5.9 / 10
EPSS score: 0.0004 (probability of exploitation in next 30 days)
EPSS percentile: 12.43% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

NVD-assigned CWE(s): CWE-269 (differs from the CNA list above)

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-30905
Assigner: mozilla
Published: May 19, 2026, 12:29:49 PM
Updated: May 20, 2026, 3:37:35 PM
EUVD base score (CVSS 3.1): 8.8 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EUVD-reported EPSS: 0.0400
Aliases: GHSA-47hh-w7m9-q45x

ENISA description: Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

EUVD references (5)

Affected products (2)

Vendor	Product	Versions	Platforms
Mozilla	Firefox	`140.11` (unaffected), `151` (unaffected)	—
Mozilla	Thunderbird	`140.11` (unaffected), `151` (unaffected)	—

Affected products — CPE 2.3 (4) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

Vendor references (5)

References embedded in the original CVE record by the assigning CNA.

Web references (14)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

http://www.mozilla.org/security/announce/2026/mfsa2026-51.html rapid7:www.mozilla.org
http://www.mozilla.org/security/announce/2026/mfsa2026-48.html rapid7:www.mozilla.org
https://attackerkb.com/topics/CVE-2026-8955 rapid7:attackerkb.com
http://www.mozilla.org/security/announce/2026/mfsa2026-46.html rapid7:www.mozilla.org
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-30905 rapid7:euvd.enisa.europa.eu
http://cwe.mitre.org/data/definitions/269.html rapid7:cwe.mitre.org
https://www.mozilla.org/security/advisories/mfsa2026-48/ tenable:www.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-50/ tenable:www.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-51/ tenable:www.mozilla.org
https://bugzilla.mozilla.org/show_bug.cgi?id=2031064 tenable:bugzilla.mozilla.org
https://nvd.nist.gov/vuln/detail/CVE-2026-8955 tenable:nvd.nist.gov
https://www.cve.org/CVERecord?id=CVE-2026-8955 tenable:www.cve.org
https://www.first.org/epss/ tenable:www.first.org
https://www.mozilla.org/security/advisories/mfsa2026-46/ tenable:www.mozilla.org

NVD-tagged references (5)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://bugzilla.mozilla.org/show_bug.cgi?id=2031064 security@mozilla.org Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-46/ security@mozilla.org Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-48/ security@mozilla.org Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-50/ security@mozilla.org Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-51/ security@mozilla.org Vendor Advisory

Remediations (14)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

CVE-2026-8955 - Vulnerability Details - OpenCVE

web:app.opencve.io

Remediation No vendor fix or workaround currently provided. OpenCVE Recommended Actions Update Firefox to version 151 or later, or to Firefox ESR 140.11 or later if using the ESR line, and update Thunderbird to version 151 or later, or to Thunderbird ESR 140.11 or later if using the ESR line.

2026-05-23 22:18 UTC
CVE-2026-8955 - Privilege escalation in the DOM: Workers component

web:cvefeed.io

The following products are affected by CVE-2026-8955 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

2026-05-23 22:18 UTC
Patch Tuesday, May 2026 Edition - Krebs on Security

web:krebsonsecurity.com

Microsoft expects that exploitation is more likely. May's Patch Tuesday is a welcome respite from April, which saw Microsoft fix a near-record 167 security flaws.

2026-05-23 22:18 UTC
Nvd - Cve-2026-8955

web:nvd.nist.gov

Official websites use .gov A .gov website belongs to an official government organization in the United States.

2026-05-23 22:18 UTC
Security Update Guide - Microsoft

web:portal.msrc.microsoft.com

The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

2026-05-23 22:18 UTC
About the security content of iOS 26.5 and iPadOS 26.5

web:support.apple.com

This document describes the security content of iOS 26.5 and iPadOS 26.5.

2026-05-23 22:18 UTC
WhatsApp Web

web:web.whatsapp.com

Log in to WhatsApp Web for simple, reliable and private messaging on your desktop. Send and receive messages and files with ease, all for free.

2026-05-23 22:18 UTC
iOS 26.5—Apple Just Gave iPhone Users 60 Reasons To Update Now - Forbes

web:www.forbes.com

Apple has released iOS 26.5, fixing a hefty list of over 60 security flaws, many of which are serious. Here's what you need to know.

2026-05-23 22:18 UTC
Oracle Critical Patch Update Advisory - April 2026

web:www.oracle.com

This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.

2026-05-23 22:18 UTC
Patch Tuesday May 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-05-23 22:18 UTC
CVE-2026-8955 - Exploits & Severity - Feedly

web:feedly.com

Patch Yes, patches are available. Firefox versions 151.0.0 and later, Firefox ESR 140.11 and later, Thunderbird 151.0.0 and later, and Thunderbird ESR 140.11 and later contain the fix .

2026-05-26 02:58 UTC
SecuriTricks - CVE-2026-8955 - 8.8/10

web:securitricks.com

CVE CVE-2026-8955 - Score : 8.8 - Source : security@mozilla.org - Description : Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

2026-05-26 02:58 UTC
CVE-2026-8955 | Ubuntu

web:ubuntu.com

Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things.

2026-05-26 02:58 UTC
CVE-2026-8955 - High Vulnerability - TheHackerWire

web:www.thehackerwire.com

How do I fix or mitigate CVE-2026-8955 ? To protect against CVE-2026-8955 , you should: (1) Apply the latest security patches from Mozilla, (2) Check official security advisories for specific remediation steps, (3) Update affected software to the latest version, and (4) Monitor your systems for any signs of exploitation.

2026-05-26 02:58 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-8955.json.

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