The existence of a specifically requested local file can be found due to the double firing of the "onerror" when the "source" attribute on…

published 2018-06-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-14491

cvss: 3.3; version 3.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 33%
public exploits: 0; none known

The existence of a specifically requested local file can be found due to the double firing of the "onerror" when the "source" attribute on a "<track>" tag refers to a file that does not exist if the source page is loaded locally. This vulnerability affects Firefox < 51.

Patch / fix

fixed in 1 distros 3

Mozilla Firefox 51

ubuntu opensuse arch linux

firefox Ubuntu 14.04 LTS 51.0.1+build2-0ubuntu0.14.04.1
firefox Ubuntu 16.04 LTS 51.0.1+build2-0ubuntu0.16.04.1

ubuntu advisories UBUNTU-CVE-2017-5387

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

firefox-esr openSUSE Tumbleweed 128.5.1-1.1
MozillaFirefox openSUSE Tumbleweed 92.0-1.2

opensuse advisories openSUSE-SU-2024:14572-1 openSUSE-SU-2024:10600-1

firefox Arch Linux 51.0.1-1

arch linux advisories AVG-157

Exploit prediction

0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1295023 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.0	3.3	CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
NVD	2.0	2.1	AV:L/AC:L/Au:N/C:N/I:P/A:N

Affected products

Mozilla Firefox

Classification

Weakness

CWE-538 Insertion of Sensitive Information into Externally-Accessible File or Directory

References

bugzilla.mozilla.org /show_bug.cgi?id=1295023
exploit, issue-tracking
mozilla.org /security/advisories/mfsa2017-01/
vendor-advisory
securitytracker.com /id/1037693
vdb-entry, third-party-advisory
securityfocus.com /bid/95763
vdb-entry, third-party-advisory

Sources

CVE List CVE-2017-5387
NVD CVE-2017-5387

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary