How severe is CVE-2026-8390?

CVE-2026-8390 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2026-8390 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-8390?

CVE-2026-8390 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-8390?

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

Does CVE-2026-8390 have an EU (EUVD) identifier?

Yes. CVE-2026-8390 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29465.

When was CVE-2026-8390 published?

CVE-2026-8390 was published on 2026-05-12 and last updated on 2026-06-30.

CVE-2026-8390

CVE-2026-8390 is a high-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 7.3. 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-416.

Key facts

Severity: High (CVSS 3.x base score 7.3)
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29465
Weakness: CWE-416
Affected product: Mozilla Firefox
Published: 2026-05-12
Last modified: 2026-06-30

Description

Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 150.0.3.

Frequently asked questions

What is CVE-2026-8390?: Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 150.0.3.
How severe is CVE-2026-8390?: CVE-2026-8390 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2026-8390 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-8390?: CVE-2026-8390 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-8390?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-8390 have an EU (EUVD) identifier?: Yes. CVE-2026-8390 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29465.
When was CVE-2026-8390 published?: CVE-2026-8390 was published on 2026-05-12 and last updated on 2026-06-30.

References

Affected products (1)

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

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Other CWE-416 (Use After Free) vulnerabilities

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CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
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