What’s Vulnerable › Vulnerabilities

CVE-2019-11730

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 20.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-07-23 · updated 2026-06-17

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.

Affected products

• Debian Linux: 8.0
• Mozilla Firefox: before 68.0 — fixed in 68.0
• Mozilla Firefox ESR: before 60.8 — fixed in 60.8
• Mozilla Thunderbird: before 60.8 — fixed in 60.8
• openSUSE Leap: 15.0, 15.1
• SUSE Package Hub: all versions

How to fix

Upgrade to a fixed version: Mozilla Firefox 68.0; Mozilla Firefox ESR 60.8; Mozilla Thunderbird 60.8. Check the vendor advisory for mitigations.

References

• http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00055.html
• http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00058.html
• http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00073.html
• http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00009.html
• http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00010.html
• https://bugzilla.mozilla.org/show_bug.cgi?id=1558299
• https://lists.debian.org/debian-lts-announce/2019/08/msg00001.html
• https://lists.debian.org/debian-lts-announce/2019/08/msg00002.html
• https://security.gentoo.org/glsa/201908-12
• https://security.gentoo.org/glsa/201908-20
• https://www.mozilla.org/security/advisories/mfsa2019-21/
• https://www.mozilla.org/security/advisories/mfsa2019-22/

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