Punycode format text will be displayed for entire qualified international domain names in some instances when a sub-domain triggers the pun…

published 2018-06-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-16813

cvss: 5.3; version 3.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.4%; EPSS 1.4% chance of exploitation in 30 days, percentile 73%
public exploits: 0; none known

Punycode format text will be displayed for entire qualified international domain names in some instances when a sub-domain triggers the punycode display instead of the primary domain being displayed in native script and the sub-domain only displaying as punycode. This could be used for limited spoofing attacks due to user confusion. This vulnerability affects Firefox < 57.

Patch / fix

fixed in 1 distros 3

Mozilla Firefox 57

ubuntu opensuse arch linux

firefox Ubuntu 14.04 LTS 57.0+build4-0ubuntu0.14.04.4
firefox Ubuntu 16.04 LTS 57.0+build4-0ubuntu0.16.04.5
firefox Ubuntu 18.04 LTS 57.0.1+build2-0ubuntu1

ubuntu advisories UBUNTU-CVE-2017-7838

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 57.0-1

arch linux advisories AVG-494

Exploit prediction

1.44% chance of exploitation in the next 30 days, higher than 73% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.0	5.3	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:P/A:N

Affected products

Mozilla Firefox

Classification

Weakness

CWE-20 Improper Input Validation

References

mozilla.org /security/advisories/mfsa2017-24/
vendor-advisory
securityfocus.com /bid/101832
vdb-entry, third-party-advisory
bugzilla.mozilla.org /show_bug.cgi?id=1399540
issue-tracking, permissions-required
securitytracker.com /id/1039803
vdb-entry, third-party-advisory

Sources

CVE List CVE-2017-7838
NVD CVE-2017-7838

Fencer Vulns 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