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CVE-2017-7800

29
FAUCET Score

CVE-2017-7800 is a critical use-after-free vulnerability in WebSockets affecting Mozilla Firefox, Firefox ESR, and Thunderbird versions prior to 55 and 52.3 respectively. This flaw allows an attacker to trigger an exploitable crash by freeing the connection object before disconnection is complete. With a CVSS score of 9.8 (CRITICAL), it presents a high risk due to its network-based attack vector, low attack complexity, and potential for high impact on confidentiality, integrity, and availability. While no public exploit code or active exploitation has been observed, and it is not listed in CISA's KEV catalog, its high severity warrants prompt patching.

Impacted Technologies

VendorProductVersion(s)CPE
8.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
6.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
6.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux_desktop:6.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
3.04%
Probability of exploitation in next 30 days
EPSS Percentile
86.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0304 is in the 77th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

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

Remediation

Patch Available

Vendor Patches (5)

mozillapatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox-0:52.3.0-3.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: thunderbird-0:52.3.0-1.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox-0:52.3.0-2.el7_4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: thunderbird-0:52.3.0-1.el7_4
View patch

Vendor Advisories (1)

redhatCVE-2017-7800Critical

Mozilla: Use-after-free in WebSockets during disconnection (MFSA 2017-19)

Aug 8, 2017

References

access.redhat.com / errata/RHSA-2017:2456
Third Party Advisory
access.redhat.com / errata/RHSA-2017:2534
Third Party Advisory
bugzilla.mozilla.org / show_bug.cgi
ExploitIssue TrackingPatchVendor Advisory
security.gentoo.org / glsa/201803-14
Third Party Advisory
debian.org / security/2017/dsa-3928
Third Party Advisory
debian.org / security/2017/dsa-3968
Third Party Advisory
mozilla.org / security/advisories/mfsa2017-18
Vendor Advisory
mozilla.org / security/advisories/mfsa2017-19
Vendor Advisory
mozilla.org / security/advisories/mfsa2017-20
Vendor Advisory
securityfocus.com / bid/100196
Third Party AdvisoryVDB Entry
securitytracker.com / id/1039124
Third Party AdvisoryVDB Entry