Skip to content
Fencer Vulns
medium 4.3

CVE-2016-5251 json

Mozilla Firefox before 48.0 allows remote attackers to spoof the location bar via crafted characters in the media type of a data: URL.

published 2016-08-05 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-6202

cvss
4.3
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 73%
public exploits
0
none known

Summary

Mozilla Firefox before 48.0 allows remote attackers to spoof the location bar via crafted characters in the media type of a data: URL.

Patch / fix

  • firefox Ubuntu 14.04 LTS 48.0+build2-0ubuntu0.14.04.1
  • firefox Ubuntu 16.04 LTS 48.0+build2-0ubuntu0.16.04.1

ubuntu advisories UBUNTU-CVE-2016-5251

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 50.1.0-1.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10071-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-5251 updated cvss 4.3

Mozilla: Location bar spoofing via data URLs with malformed/invalid mediatypes (MFSA 2016-66)

  • Red Hat Enterprise Linux 5 firefox, thunderbird Red Hat Enterprise Linux 6 firefox, thunderbird Red Hat Enterprise Linux 7 firefox, thunderbird
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.47% 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 4.3 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

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.