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Fencer Intel
high 8.2

CVE-2017-7813 json

Inside the JavaScript parser, a cast of an integer to a narrower type can result in data read from outside the buffer being parsed.

published 2018-06-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-16788

cvss
8.2
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known

Summary

Inside the JavaScript parser, a cast of an integer to a narrower type can result in data read from outside the buffer being parsed. This usually results in a non-exploitable crash, but can leak a limited amount of information from memory if it matches JavaScript identifier syntax. This vulnerability affects Firefox < 56.

Patch / fix

  • Mozilla Firefox 56
  • firefox Ubuntu 14.04 LTS 56.0+build6-0ubuntu0.14.04.1
  • firefox Ubuntu 16.04 LTS 56.0+build6-0ubuntu0.16.04.1
  • firefox Ubuntu 18.04 LTS 56.0+build6-0ubuntu1

ubuntu advisories UBUNTU-CVE-2017-7813

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

Exploit prediction

1.56% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1383951 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 8.2 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:N/A:P

Affected products

  • Mozilla Firefox

Classification

Weakness
  • CWE-125 Out-of-bounds Read
  • CWE-704 Incorrect Type Conversion or Cast

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.