How severe is CVE-2026-8091?

CVE-2026-8091 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-8091 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-8091?

CVE-2026-8091 primarily affects Mozilla Firefox. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-8091?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-8091 have an EU (EUVD) identifier?

Yes. CVE-2026-8091 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28362.

When was CVE-2026-8091 published?

CVE-2026-8091 was published on 2026-05-07 and last updated on 2026-06-30.

CVE-2026-8091

CVE-2026-8091 is a critical-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-754.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-28362
Weakness: CWE-754
Affected product: Mozilla Firefox
Published: 2026-05-07
Last modified: 2026-06-30

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.

Frequently asked questions

What is CVE-2026-8091?: 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.
How severe is CVE-2026-8091?: CVE-2026-8091 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-8091 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-8091?: CVE-2026-8091 primarily affects Mozilla Firefox. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-8091?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-8091 have an EU (EUVD) identifier?: Yes. CVE-2026-8091 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28362.
When was CVE-2026-8091 published?: CVE-2026-8091 was published on 2026-05-07 and last updated on 2026-06-30.

References

Affected products (2)

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

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