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Fencer Vulns
critical 9.8

CVE-2017-5391 json

Special "about:" pages used by web content, such as RSS feeds, can load privileged "about:" pages in an iframe.

published 2018-06-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-14495

cvss
9.8
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.7%
EPSS 1.7% chance of exploitation in 30 days, percentile 77%
public exploits
0
none known

Summary

Special "about:" pages used by web content, such as RSS feeds, can load privileged "about:" pages in an iframe. If a content-injection bug were found in one of those pages this could allow for potential privilege escalation. This vulnerability affects Firefox < 51.

Patch / fix

  • Mozilla Firefox 51
  • 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-2017-5391

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 51.0.1-1

arch linux advisories AVG-157

Exploit prediction

1.73% chance of exploitation in the next 30 days, higher than 77% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 9.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Mozilla Firefox

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.