How severe is CVE-2026-100813?

CVE-2026-100813 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-100813 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-100813?

CVE-2026-100813 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-2026-100813?

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.

When was CVE-2026-100813 published?

CVE-2026-100813 was published on 2026-09-29 and last updated on 2026-10-05.

CVE-2026-100813

CVE-2026-100813 is a high-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 8.8. 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-763.

Key facts

Severity: High (CVSS 3.x base score 8.8)
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-763
Affected product: Mozilla Firefox
Published: 2026-09-29
Last modified: 2026-10-05

Description

Invalid pointer in the JavaScript Engine: JIT component. This vulnerability was fixed in Thunderbird 157 and Firefox 157.

Frequently asked questions

What is CVE-2026-100813?: Invalid pointer in the JavaScript Engine: JIT component. This vulnerability was fixed in Thunderbird 157 and Firefox 157.
How severe is CVE-2026-100813?: CVE-2026-100813 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-100813 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-100813?: CVE-2026-100813 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-2026-100813?: 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.
When was CVE-2026-100813 published?: CVE-2026-100813 was published on 2026-09-29 and last updated on 2026-10-05.

References

Affected products (2)

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

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