Is CVE-2026-8091 in the CISA KEV catalog?

No. CVE-2026-8091 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-8091?

CVE-2026-8091 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2026-8091?

CVE-2026-8091 has an EPSS score of 0.44% (36th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-8091?

Upgrade firefox on debian unstable to 150.0-1 or later. Fixes are available for 4 affected products.

CVE & CISA-KEV Catalog

CVE-2026-8091

CRITICAL

9.8

CVSS v3

NVD

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.

CWE-754 CWE-805

How to fix

Remediation Available

firefoxDebian

Fixed in:150.0-1CVE-2026-8091

DeveloperEditionWindows application

Affected:140.0 140.10.1Fixed in:140.10.1Mozilla

Affected:115.35.2Fixed in:115.35.2Mozilla

Mozilla Firefox (en-US)Windows application

Affected:115.35.2Fixed in:115.35.2Mozilla

Affected:140.0 140.10.1Fixed in:140.10.1Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:140.0 140.10.1Fixed in:140.10.1Mozilla

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

0.44%probability of exploitation in 30 days

36thpercentile

Low risk: more likely to be exploited than 36% of all known CVEs.

References

Vendor Advisory5

Other references4

Related Vulnerabilities

Other CWE-754 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-4367	High	8.8	73%	-	Fix
CVE-2022-39288	High	7.5	59%	-	Fix
CVE-2023-30591	High	7.5	54%	-	-
CVE-2023-41993	High	8.8	29%	KEV	Fix
CVE-2024-43044	High	8.8	29%	-	Fix
CVE-2024-3393	High	7.5	27%	KEV	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-15.