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CVE-2017-7756

26
FAUCET Score

CVE-2017-7756 is a critical use-after-free and use-after-scope vulnerability in Firefox, Firefox ESR, and Thunderbird versions prior to 54 and 52.2 respectively, occurring when logging errors from XML HTTP Request (XHR) headers. With a CVSS score of 9.8, this vulnerability allows for remote, low-complexity attacks without user interaction, potentially leading to a complete compromise of confidentiality, integrity, and availability. While no public exploit code or active exploitation has been confirmed, the vulnerability has garnered some community discussion and media coverage, indicating awareness within the cybersecurity landscape.

Impacted Technologies

VendorProductVersion(s)CPE
< 52.2.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
< 54.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
< 52.2.0CPE matchmatch criteria
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*

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
2.67%
Probability of exploitation in next 30 days
EPSS Percentile
84.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0267 is in the 75th 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)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox-0:52.2.0-1.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: thunderbird-0:52.2.0-1.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox-0:52.2.0-1.el7_3
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: thunderbird-0:52.2.0-1.el7_3
View patch
mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2017-7756Important

Mozilla: Use-after-free and use-after-scope logging XHR header errors (MFSA 2017-16)

Jun 14, 2017

References

access.redhat.com / errata/RHSA-2017:1440
Third Party Advisory
access.redhat.com / errata/RHSA-2017:1561
Third Party Advisory
bugzilla.mozilla.org / show_bug.cgi
Issue TrackingVendor Advisory
debian.org / security/2017/dsa-3881
Third Party Advisory
debian.org / security/2017/dsa-3918
Third Party Advisory
mozilla.org / security/advisories/mfsa2017-15
Vendor Advisory
mozilla.org / security/advisories/mfsa2017-16
Vendor Advisory
mozilla.org / security/advisories/mfsa2017-17
Vendor Advisory
securityfocus.com / bid/99057
Third Party AdvisoryVDB Entry
securitytracker.com / id/1038689
Third Party AdvisoryVDB Entry