Skip to content
Fencer Intel
medium 6.1

CVE-2017-7839 json

Control characters prepended before "javascript:" URLs pasted in the addressbar can cause the leading characters to be ignored and the past…

published 2018-06-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-16814

cvss
6.1
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 66%
public exploits
0
none known

Summary

Control characters prepended before "javascript:" URLs pasted in the addressbar can cause the leading characters to be ignored and the pasted JavaScript to be executed instead of being blocked. This could be used in social engineering and self-cross-site-scripting (self-XSS) attacks where users are convinced to copy and paste text into the addressbar. This vulnerability affects Firefox < 57.

Patch / fix

  • Mozilla Firefox 57
  • 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-2017-7839

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

  • firefox Arch Linux 57.0-1

arch linux advisories AVG-494

Exploit prediction

1.12% chance of exploitation in the next 30 days, higher than 66% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 6.1 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • Mozilla Firefox

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

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.