How severe is CVE-2022-26387?

CVE-2022-26387 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2022-26387 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2022-26387?

CVE-2022-26387 primarily affects Mozilla Firefox. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2022-26387?

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-2022-26387 published?

CVE-2022-26387 was published on 2022-12-22 and last updated on 2026-06-17.

CVE-2022-26387

CVE-2022-26387 is a high-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 7.5. 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-367.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-367
Affected product: Mozilla Firefox
Published: 2022-12-22
Last modified: 2026-06-17

Description

When installing an add-on, Firefox verified the signature before prompting the user; but while the user was confirming the prompt, the underlying add-on file could have been modified and Firefox would not have noticed. This vulnerability affects Firefox < 98, Firefox ESR < 91.7, and Thunderbird < 91.7.

Frequently asked questions

What is CVE-2022-26387?: When installing an add-on, Firefox verified the signature before prompting the user; but while the user was confirming the prompt, the underlying add-on file could have been modified and Firefox would not have noticed. This vulnerability affects Firefox < 98, Firefox ESR < 91.7, and Thunderbird < 91.7.
How severe is CVE-2022-26387?: CVE-2022-26387 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2022-26387 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2022-26387?: CVE-2022-26387 primarily affects Mozilla Firefox. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2022-26387?: 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-2022-26387 published?: CVE-2022-26387 was published on 2022-12-22 and last updated on 2026-06-17.

References

Affected products (3)

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

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