How severe is CVE-2018-12391?

CVE-2018-12391 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-2018-12391 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-12391?

CVE-2018-12391 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-2018-12391?

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-2018-12391 published?

CVE-2018-12391 was published on 2019-02-28 and last updated on 2026-06-17.

CVE-2018-12391

CVE-2018-12391 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-863.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 9.3
EPSS exploit prediction: 2% (79th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-863
Affected product: Mozilla Firefox
Published: 2019-02-28
Last modified: 2026-06-17

Description

During HTTP Live Stream playback on Firefox for Android, audio data can be accessed across origins in violation of security policies. Because the problem is in the underlying Android service, this issue is addressed by treating all HLS streams as cross-origin and opaque to access. *Note: this issue only affects Firefox for Android. Desktop versions of Firefox are unaffected.*. This vulnerability affects Firefox < 63, Firefox ESR < 60.3, and Thunderbird < 60.3.

Frequently asked questions

What is CVE-2018-12391?: During HTTP Live Stream playback on Firefox for Android, audio data can be accessed across origins in violation of security policies. Because the problem is in the underlying Android service, this issue is addressed by treating all HLS streams as cross-origin and opaque to access. *Note: this issue only affects Firefox for Android. Desktop versions of Firefox are unaffected.*. This vulnerability affects Firefox < 63, Firefox ESR < 60.3, and Thunderbird < 60.3.
How severe is CVE-2018-12391?: CVE-2018-12391 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-2018-12391 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-12391?: CVE-2018-12391 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-2018-12391?: 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-2018-12391 published?: CVE-2018-12391 was published on 2019-02-28 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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