CVE-2016-7943

The XListFonts function in X.org libX11 before 1.6.4 might allow remote X servers to gain privileges via vectors involving length fields, which trigger out-of-bounds write operations.

Published: 2016-12-13 Last update: 2026-05-06 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-7943 is rated High Risk (70.6/100): CVSS Critical severity, with high exploitation likelihood (EPSS 4.50%, 90th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2016-7943

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 4.71% 4.50% -0.22%
2 2026-06-04 4.39% 4.71% +0.32%
3 2026-02-27 — 4.39% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-7943

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.0 CRITICAL
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2016-7943

OS Trackers for CVE-2016-7943

vendor priority summary link
debian low CVE-2016-7943 low priority: Debian including 1 source packages (libx11), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-7943
gentoo high CVE-2016-7943: 1 GLSA(s) (201704-03), 8 atom(s) (x11-base/xorg-server, x11-libs/libICE, …); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2016-7943
redhat medium — https://access.redhat.com/security/cve/CVE-2016-7943
ubuntu low CVE-2016-7943 low priority: Ubuntu including 1 source packages (libx11), 8 status rows across 8 suites (artful, bionic, precise, trusty, upstream, xenial, yakkety, zesty): ignored 4, released 4. https://ubuntu.com/security/CVE-2016-7943

Affected software / configurations for CVE-2016-7943

Vendor Product Version Raw CPE
fedoraproject fedora 25 cpe:2.3:o:fedoraproject:fedora:25:*:*:*:*:*:*:*
x.org libx11 <= 1.6.3 cpe:2.3:a:x.org:libx11:*:*:*:*:*:*:*:*

References for CVE-2016-7943

cvelogic Threat Intelligence