CVE-2026-8091

Description

Incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, Thunderbird 140.10.1, and Firefox ESR 115.35.2.

Overview

State: PUBLISHED
Assigner (CNA): mozilla
CVSS severity: critical
CVSS score: 9.8 / 10
CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Effective score: 9.8 / 10 CRITICAL source: CNA overview
CWE(s): —
Reserved: 2026-05-07
Published: 2026-05-07 14:45 UTC
Last updated: 2026-05-09 00:33 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/8xxx/CVE-2026-8091.json
Linked Threat: CVE-2026-8091 — CVE-2026-8091

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: 2026-05-07 13:16:14 UTC
NVD last modified: 2026-05-11 15:20:21 UTC
NVD CVSS v3.1: 9.8 / 10 CRITICAL source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploitability subscore: 3.9 / 10
Impact subscore: 5.9 / 10
EPSS score: 0.0002 (probability of exploitation in next 30 days)
EPSS percentile: 6.81% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

NVD-assigned CWE(s): CWE-754 (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-2026-28362
Assigner: mozilla
Published: May 7, 2026, 12:45:05 PM
Updated: May 8, 2026, 10:33:49 PM
EUVD base score (CVSS 3.1): 9.8 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EUVD-reported EPSS: 0.0200
Vendors: Mozilla
Products: Firefox

ENISA description: Incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, Thunderbird 140.10.1, and Firefox ESR 115.35.2.

EUVD references (6)

Affected products (2)

Vendor	Product	Versions	Platforms
Mozilla	Firefox	`115.35.2` (unaffected), `140.10.1` (unaffected), `150` (unaffected)	—
Mozilla	Thunderbird	`140.10.1` (unaffected), `150` (unaffected)	—

Affected products — CPE 2.3 (2) 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:thunderbird:*:*:*:*:-:*:*:*

Vendor references (6)

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

MITRE references (6) cveawg.mitre.org

Pulled from MITRE's CVE Services API by the 🛰 Backfill from MITRE button.

Web references (11)

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/mfsa2026-39.html rapid7:www.mozilla.org
http://www.mozilla.org/security/announce/2026/mfsa2026-41.html rapid7:www.mozilla.org
http://www.mozilla.org/security/announce/2026/mfsa2026-36.html rapid7:www.mozilla.org
http://www.mozilla.org/security/announce/2026/mfsa2026-42.html rapid7:www.mozilla.org
http://www.mozilla.org/security/announce/2026/mfsa2026-30.html rapid7:www.mozilla.org
http://cwe.mitre.org/data/definitions/754.html rapid7:cwe.mitre.org
https://attackerkb.com/topics/CVE-2026-8091 rapid7:attackerkb.com
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-28362 rapid7:euvd.enisa.europa.eu
https://www.first.org/epss/ tenable:www.first.org
https://nvd.nist.gov/vuln/detail/CVE-2026-8091 tenable:nvd.nist.gov
https://www.cve.org/CVERecord?id=CVE-2026-8091 tenable:www.cve.org

NVD-tagged references (6)

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=2029301 security@mozilla.org Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-30/ security@mozilla.org Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-33/ security@mozilla.org Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-36/ security@mozilla.org Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-39/ security@mozilla.org Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-42/ security@mozilla.org Vendor Advisory

Remediations (15)

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

CISA Warns of Exploited Microsoft Defender 0-Day Flaws

web:cyberpress.org

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added two actively exploited Microsoft Defender vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog, issuing an urgent remediation directive for federal agencies with a due date of June 3, 2026 .

2026-05-23 21:08 UTC
Microsoft Patch Tuesday March 2026 - 78 Vulnerabilities Fixed ...

web:cybersecuritynews.com

Microsoft released its March 2026 Patch Tuesday security update on March 10, 2026 , addressing 78 vulnerabilities across Windows, Microsoft Office, Azure, SQL Server, and .NET. The update includes one actively exploited zero-day vulnerability and multiple Critical-rated flaws demanding immediate attention from security teams. The most urgent fix this month is CVE - 2026 -21262, the sole zero-day ...

2026-05-23 21:08 UTC
Nvd - Cve-2026-41091

web:nvd.nist.gov

An official website of the United States government NVD MENU

2026-05-23 21:08 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 21:08 UTC
Microsoft Patches Two Actively Exploited Defender Zero-Days on Windows

web:windowsreport.com

Microsoft patched two actively exploited Defender zero-days affecting Windows systems and security components.

2026-05-23 21:08 UTC
Microsoft warns of new Defender zero-days exploited in attacks

web:www.bleepingcomputer.com

On Wednesday, Microsoft started rolling out security patches for two Defender vulnerabilities that have been exploited in zero-day attacks.

2026-05-23 21:08 UTC
Microsoft patches two zero-day flaws in Defender - CSO Online

web:www.csoonline.com

Microsoft released emergency fixes for two zero-day vulnerabilities in the malware protection components of Microsoft Defender. The flaws allow local attackers to gain system-level privileges or ...

2026-05-23 21:08 UTC
2 New Microsoft Defender Zero-Days Exploited—Patch Now ... - Forbes

web:www.forbes.com

Microsoft has confirmed an emergency security update as CISA warns that two new Defender zero-days are being exploited by attackers.

2026-05-23 21:08 UTC
January 2026 Patch Tuesday - ivanti.com

web:www.ivanti.com

For January 2026 Patch Tuesday, your top priorities are the Windows OS update, which resolves a known exploited vulnerability, and the Mozilla browser update.

2026-05-23 21:08 UTC
Microsoft February 2026 Patch Tuesday Fixes 50 ... - LinkedIn

web:www.linkedin.com

Microsoft has released its February 2026 Patch Tuesday security updates, fixing a total of 59 vulnerabilities across Windows, Microsoft Office, and core system components. The update includes ...

2026-05-23 21:08 UTC
Microsoft Patch Tuesday February 2026 - 54 Vulnerabilities Fixed ...

web:cybersecuritynews.com

Microsoft released its February 2026 Patch Tuesday updates on February 10, addressing 54 vulnerabilities, including six zero-days across Windows, Office, Azure, and developer tools.

2026-05-26 02:49 UTC
Microsoft January 2026 Security Updates (FYI) - Microsoft Q&A

web:learn.microsoft.com

January 2026 Security Updates This release consists of the following 112 Microsoft CVEs : Tag CVE Base Score CVSS Vector Exploitability FAQs? Workarounds? Mitigations ? Windows Deployment Services CVE - 2026 -0386 SQL Server CVE - 2026 -20803 Windows Hello…

2026-05-26 02:49 UTC
Microsoft March 2026 Patch Tuesday fixes 2 zero-days, 79 flaws

web:www.bleepingcomputer.com

Today is Microsoft's March 2026 Patch Tuesday with security updates for 79 flaws, including 2 publicly disclosed zero-day vulnerabilities.

2026-05-26 02:49 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.

2026-05-26 02:49 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 02:49 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-8091.json.

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