How severe is CVE-2024-9398?

CVE-2024-9398 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2024-9398 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2024-9398?

CVE-2024-9398 primarily affects Mozilla Firefox. In total, 9 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2024-9398?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2024-9398 have an EU (EUVD) identifier?

Yes. CVE-2024-9398 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-49913.

When was CVE-2024-9398 published?

CVE-2024-9398 was published on 2024-10-01 and last updated on 2026-06-17.

CVE-2024-9398

CVE-2024-9398 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 5.3. 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-203.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 1% (43rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2024-49913
Weakness: CWE-203
Affected product: Mozilla Firefox
Published: 2024-10-01
Last modified: 2026-06-17

Description

By checking the result of calls to `window.open` with specifically set protocol handlers, an attacker could determine if the application which implements that protocol handler is installed. This vulnerability affects Firefox < 131, Firefox ESR < 128.3, Thunderbird < 128.3, and Thunderbird < 131.

Frequently asked questions

What is CVE-2024-9398?: By checking the result of calls to `window.open` with specifically set protocol handlers, an attacker could determine if the application which implements that protocol handler is installed. This vulnerability affects Firefox < 131, Firefox ESR < 128.3, Thunderbird < 128.3, and Thunderbird < 131.
How severe is CVE-2024-9398?: CVE-2024-9398 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2024-9398 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2024-9398?: CVE-2024-9398 primarily affects Mozilla Firefox. In total, 9 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2024-9398?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2024-9398 have an EU (EUVD) identifier?: Yes. CVE-2024-9398 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-49913.
When was CVE-2024-9398 published?: CVE-2024-9398 was published on 2024-10-01 and last updated on 2026-06-17.

References

Affected products (9)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:129.0:beta:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:129.0:beta2:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:129.0:beta3:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:129.0:beta4:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:129.0:beta5:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:129.0:beta6:*:*:*:*:*:*

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