CVE-2026-8949

Description

Integer overflow in the Widget: Win32 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: 7.5 / 10
CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Effective score: 7.5 / 10 HIGH source: CNA overview
CWE(s): —
Reserved: 2026-05-19
Published: 2026-05-19 12:29 UTC
Last updated: 2026-05-19 17:10 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/8xxx/CVE-2026-8949.json
Linked Threat: CVE-2026-8949 — CVE-2026-8949

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 14:49:05 UTC
NVD CVSS v3.1: 7.5 / 10 HIGH source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploitability subscore: 3.9 / 10
Impact subscore: 3.6 / 10
EPSS score: 0.0005 (probability of exploitation in next 30 days)
EPSS percentile: 14.61% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

NVD-assigned CWE(s): CWE-190 (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-2026-30899
Assigner: mozilla
Published: May 19, 2026, 12:29:40 PM
Updated: May 19, 2026, 5:10:47 PM
EUVD base score (CVSS 3.1): 7.5 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EUVD-reported EPSS: 0.0600
Aliases: GHSA-wpxg-v53p-m79m

ENISA description: Integer overflow in the Widget: Win32 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-2026-8949 rapid7:attackerkb.com
http://www.mozilla.org/security/announce/2026/mfsa2026-46.html rapid7:www.mozilla.org
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-30899 rapid7:euvd.enisa.europa.eu
http://cwe.mitre.org/data/definitions/190.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=1355639 tenable:bugzilla.mozilla.org
https://nvd.nist.gov/vuln/detail/CVE-2026-8949 tenable:nvd.nist.gov
https://www.cve.org/CVERecord?id=CVE-2026-8949 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=1355639 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 (17)

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

Microsoft acknowledges May 2026 Windows 11 security update install ...

web:betanews.com

Another month, another update for Windows which is problematic. This time around, it is the May 2026 Windows 11 security update - or the KB5089549 update.

2026-05-23 22:18 UTC
Oracle Critical Patch Update (CPU) April 2026 for Oracle Java SE

web:docs.oracle.com

Oracle Critical Patch Update (CPU) April 2026 for Oracle Java SE Services: Java Management Release Date: April 21, 2026

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-2026-8949

web:nvd.nist.gov

An official website of the United States government Here's how you know

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
April 2026 Patch Tuesday: Updates and Analysis | CrowdStrike

web:www.crowdstrike.com

Microsoft's April 2026 Patch Tuesday addresses 164 CVEs , featuring 8 Critical vulnerabilities, one exploited zero-day, and one disclosed zero-day.

2026-05-23 22:18 UTC
Emergency patch issued for Microsoft Office, 365 over hacking threat - MSN

web:www.msn.com

Original story: Microsoft has released an emergency patch for a vulnerability in the company's Office programs that's already being exploited by hackers.

2026-05-23 22:18 UTC
CVE-2026-8949 - High Vulnerability - TheHackerWire

web:www.thehackerwire.com

CVE-2026-8949 is a High severity vulnerability (CVSS 7.5). Integer overflow in the Widget: Win32 component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and...

2026-05-23 22:18 UTC
Windows 11 April 2026 Update tested: What's new, improved and fixed

web:www.windowslatest.com

Windows 11 April 2026 update adds Narrator Copilot support, faster Settings, File Explorer fixes, and key security improvements.

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-2026-8949 - Vulnerability Details - OpenCVE

web:app.opencve.io

Affected Systems Users running any version of Firefox or Thunderbird older than the patched releases are affected. The vulnerability is confined to the Widget: Win32 component within these products. ESR builds remain vulnerable until the specified ESR release numbers.

2026-05-26 02:58 UTC
Category: Patch Tuesday | Qualys

web:blog.qualys.com

Microsoft and Adobe Patch Tuesday, April 2026 Security Update Review Posted in Patch Tuesday, Vulnerabilities and Threat Research 7 Diksha Ojha March 11, 2026 - 8 min read

2026-05-26 02:58 UTC
Microsoft Patch Tuesday for May 2026 — Snort rules and prominent ...

web:blog.talosintelligence.com

Microsoft has released its monthly security update for May 2026 , which includes 137 vulnerabilities affecting a range of products, including 16 that Microsoft marked as "critical".

2026-05-26 02:58 UTC
Addressing Exchange Server May 2026 vulnerability CVE-2026-42897

web:techcommunity.microsoft.com

We wanted to tell you how to address the Exchange Server May 2026 vulnerability CVE - 2026 -42897.

2026-05-26 02:58 UTC
Microsoft Confirms Active 0-Day Exploit—Check Emergency Mitigation

web:www.forbes.com

Updated May 17: This article, originally published May 16, has been updated to include further details on the emergency mitigation process recommended after the CVE - 2026 -42897 Microsoft Exchange ...

2026-05-26 02:58 UTC
The May 2026 Windows Update is Breaking Things - Here's the Fix

web:www.majorgeeks.com

But if you're not so fortunate, here's what you can do to fix this mess. Apply Known Issue Rollback (KIR) The Windows release health page has finally acknowledged the issue, after a slight delay. However, it only mentions installation failures, not the other problems users have complained about. But we'll take what we can get, I guess.

2026-05-26 02:58 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.

2026-05-26 02:58 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-8949.json.

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