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CVE-2016-5259

26
FAUCET Score

CVE-2016-5259 is a use-after-free vulnerability affecting Mozilla Firefox versions before 48.0 and Firefox ESR 45.x before 45.3, as well as Oracle Firefox and Oracle Linux. This flaw allows remote attackers to execute arbitrary code by manipulating a script to close its own Service Worker within a nested sync event loop. It carries a high CVSSv3 score of 8.8, indicating a network-based attack with low complexity that can lead to high confidentiality, integrity, and availability impacts. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 47.0.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
45.1.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:45.1.0:*:*:*:*:*:*:*
45.1.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:45.1.1:*:*:*:*:*:*:*
45.2.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:45.2.0:*:*:*:*:*:*:*
45.3.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:45.3.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

8.8HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
3.26%
Probability of exploitation in next 30 days
EPSS Percentile
87.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.0326 is in the 86th percentile among its peer group of 14,825 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.1 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: firefox-0:45.3.0-1.el5_11
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox-0:45.3.0-1.el6_8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox-0:45.3.0-1.el7_2
View patch
mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2016-5259Critical

Mozilla: Use-after-free in service workers with nested sync events (MFSA 2016-73)

Aug 2, 2016

References

lists.opensuse.org / opensuse-security-announce/2016-08/msg00004.html
lists.opensuse.org / opensuse-security-announce/2016-08/msg00029.html
rhn.redhat.com / errata/RHSA-2016-1551.html
bugzilla.mozilla.org / show_bug.cgi
ExploitIssue Tracking
security.gentoo.org / glsa/201701-15
debian.org / security/2016/dsa-3640
mozilla.org / security/announce/2016/mfsa2016-73.html
Vendor Advisory
oracle.com / technetwork/topics/security/linuxbulletinjul2016-3090544.html
Third Party Advisory
securityfocus.com / bid/92258
securitytracker.com / id/1036508
ubuntu.com / usn/USN-3044-1