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CVE-2017-5439

31
FAUCET Score

CVE-2017-5439 is a critical use-after-free vulnerability in Mozilla Firefox and Thunderbird, affecting versions prior to Firefox 53, Firefox ESR 52.1, and Thunderbird 52.1. This flaw, stemming from improper handling of XSLT template parameters, can lead to an exploitable crash. With a CVSS score of 9.8 (CRITICAL), it is easily exploitable over the network with low attack complexity, potentially leading to complete compromise of confidentiality, integrity, and availability. While no public exploit code exists in Metasploit or ExploitDB, and it is not listed in CISA's KEV catalog, the vulnerability has garnered significant community discussion, indicating awareness among researchers.

Impacted Technologies

VendorProductVersion(s)CPE
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:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:*:*:*:*:*:*:*

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
3.62%
Probability of exploitation in next 30 days
EPSS Percentile
88.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0362 is in the 81st percentile among its peer group of 36,862 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

No media coverage found for this CVE.

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

Remediation

Patch Available

Vendor Patches (7)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox-0:52.1.0-2.el7_3
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox-0:52.1.0-2.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: thunderbird-0:52.1.0-1.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: thunderbird-0:52.1.0-1.el7_3
View patch
mozillavendor investigatingvia nvd_reference
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: thunderbird
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: firefox

Vendor Advisories (1)

redhatCVE-2017-5439Important

Mozilla: Use-after-free in nsTArray Length() during XSLT processing (MFSA 2017-11, MFSA 2017-12)

Apr 19, 2017

References

access.redhat.com / errata/RHSA-2017:1104
Third Party Advisory
access.redhat.com / errata/RHSA-2017:1106
Third Party Advisory
access.redhat.com / errata/RHSA-2017:1201
Third Party Advisory
bugzilla.mozilla.org / show_bug.cgi
ExploitIssue TrackingVendor Advisory
debian.org / security/2017/dsa-3831
Third Party Advisory
mozilla.org / security/advisories/mfsa2017-10
Vendor Advisory
mozilla.org / security/advisories/mfsa2017-11
Vendor Advisory
mozilla.org / security/advisories/mfsa2017-12
Vendor Advisory
mozilla.org / security/advisories/mfsa2017-13
Vendor Advisory
securityfocus.com / bid/103053
Third Party AdvisoryVDB Entry
securityfocus.com / bid/97940
Third Party AdvisoryVDB Entry
securitytracker.com / id/1038320
Third Party AdvisoryVDB Entry