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Vulnerability record · CVE-2019-11730 · published 23 July 2019

CVE-2019-11730: Mozilla firefox vulnerability

Mozilla · Firefox

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.

6.5 CVSS 3.1 Medium EPSS 20% · top 2.6%
6.5CVSS 3.1 base score, v2 4.3
20%EPSS exploitation probability, 30 days
NoNot in CISA KEV
6Affected product versions listed by NVD
26References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected products

6 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00055.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00058.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00073.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00009.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00010.html Mailing ListThird Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1558299 Issue TrackingPermissions Required
https://lists.debian.org/debian-lts-announce/2019/08/msg00001.html Mailing ListThird Party Advisory
https://lists.debian.org/debian-lts-announce/2019/08/msg00002.html Mailing ListThird Party Advisory
https://security.gentoo.org/glsa/201908-12 Third Party Advisory
https://security.gentoo.org/glsa/201908-20 Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2019-21/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-22/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-23/ Vendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00055.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00058.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00073.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00009.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00010.html Mailing ListThird Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1558299 Issue TrackingPermissions Required
https://lists.debian.org/debian-lts-announce/2019/08/msg00001.html Mailing ListThird Party Advisory
https://lists.debian.org/debian-lts-announce/2019/08/msg00002.html Mailing ListThird Party Advisory
https://security.gentoo.org/glsa/201908-12 Third Party Advisory
https://security.gentoo.org/glsa/201908-20 Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2019-21/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-22/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-23/ Vendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2019-11730), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.