CVE-2019-11730

CVE-2019-11730 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 6.5. Its EPSS exploit-prediction score of 20% places it in the 97th percentile, indicating an elevated likelihood of exploitation.

Key facts

Description

A vulnerability exists where if a user opens a locally saved HTML file, this file can use file: URIs to access other files in the same directory or sub-directories if the names are known or guessed. The Fetch API can then be used to read the contents of any files stored in these directories and they may uploaded to a server. It was demonstrated that in combination with a popular Android messaging app, if a malicious HTML attachment is sent to a user and they opened that attachment in Firefox, due to that app's predictable pattern for locally-saved file names, it is possible to read attachments the victim received from other correspondents. This vulnerability affects Firefox ESR < 60.8, Firefox < 68, and Thunderbird < 60.8.

Frequently asked questions

What is CVE-2019-11730?
A vulnerability exists where if a user opens a locally saved HTML file, this file can use file: URIs to access other files in the same directory or sub-directories if the names are known or guessed. The Fetch API can then be used to read the contents of any files stored in these directories and they may uploaded to a server. It was demonstrated that in combination with a popular Android messaging app, if a malicious HTML attachment is sent to a user and they opened that attachment in Firefox, due to that app's predictable pattern for locally-saved file names, it is possible to read attachments the victim received from other correspondents. This vulnerability affects Firefox ESR < 60.8, Firefox < 68, and Thunderbird < 60.8.
How severe is CVE-2019-11730?
CVE-2019-11730 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2019-11730 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 20% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-11730?
CVE-2019-11730 primarily affects Mozilla Firefox. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-11730?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2019-11730 published?
CVE-2019-11730 was published on 2019-07-23 and last updated on 2026-06-17.

References

Affected products (7)

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