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CVE-2016-7943

The XListFonts function in X.org libX11 before 1.6.4 might allow remote X servers to gain...

9.8 CriticalFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

4.46%Up 2.9 points since Feb 4, 2022
90%50%10%1%

What each source reports

NVD Score used 9.8

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.

Record
CVE-2016-7943
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0
7.5 HighAV:N/AC:L/Au:N/C:P/I:P/A:P
Weakness
CWE-787
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2016-7943
Updated
2026-11-02
EUVDEUVD-2016-8792 No score

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.

Record
EUVD-2016-8792
Updated
2026-11-03
GitHub AdvisoriesGHSA-84fh-jqg7-vh26 9.8

The XListFonts function in X.org libX11 before 1.6.4 might allow remote X servers to gain...

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.

Record
GHSA-84fh-jqg7-vh26
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-787
Updated
2026-11-02
OSVALPINE-CVE-2016-7943 9.8

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.

Record
ALPINE-CVE-2016-7943
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVBELL-CVE-2016-7943 9.8

CVE-2016-7943 does not affect BellSoft software

Record
BELL-CVE-2016-7943
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
Show 5 moreShow less
OSV 9.8

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.

Record
CVE-2016-7943
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2016-7943 9.8

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.

Record
DEBIAN-CVE-2016-7943
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2016-7943 9.8

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.

Record
UBUNTU-CVE-2016-7943
CVSS 3.0
9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVMGASA-2018-0011 No score

Updated X11 client libraries packages fix security vulnerability

The XvQueryAdaptors and XvQueryEncodings functions in X.org libXv before 1.0.11 allow remote X servers to trigger out-of-bounds memory access operations via vectors involving length specifications in received data (CVE-2016-5407).

The XGetImage function in X.org libX11 before 1.6.4 might allow remote X servers to gain privileges via vectors involving image type and geometry, which triggers out-of-bounds read operations (CVE-2016-7942).

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 (CVE-2016-7943).

Integer overflow in X.org libXfixes before 5.0.3 on 32-bit platforms might allow remote X servers to gain privileges via a length value of INT_MAX, which triggers the client to stop reading data and get out of sync (CVE-2016-7944).

Multiple integer overflows in X.org libXi before 1.7.7 allow remote X servers to cause a denial of service (out-of-bounds memory access or infinite loop) via vectors involving length fields (CVE-2016-7945).

X.org libXi before 1.7.7 allows remote X servers to cause a denial of service (infinite loop) via vectors involving length fields (CVE-2016-7946).

Multiple integer overflows in X.org libXrandr before 1.5.1 allow remote X servers to trigger out-of-bounds write operations via a crafted response (CVE-2016-7947).

X.org libXrandr before 1.5.1 allows remote X servers to trigger out-of-bounds write operations by leveraging mishandling of reply data (CVE-2016-7948).

Multiple buffer overflows in the XvQueryAdaptors and XvQueryEncodings functions in X.org libXrender before 0.9.10 allow remote X servers to trigger out-of-bounds write operations via vectors involving length fields (CVE-2016-7949).

The XRenderQueryFilters function in X.org libXrender before 0.9.10 allows remote X servers to trigger out-of-bounds write operations via vectors involving filter name lengths (CVE-2016-7950).

Multiple integer overflows in X.org libXtst before 1.2.3 allow remote X servers to trigger out-of-bounds memory access operations by leveraging the lack of range checks (CVE-2016-7951).

X.org libXtst before 1.2.3 allows remote X servers to cause a denial of service (infinite loop) via a reply in the XRecordStartOfData, XRecordEndOfData, or XRecordClientDied category without a client sequence and with attached data (CVE-2016-7952).

Buffer underflow in X.org libXvMC before 1.0.10 allows remote X servers to have unspecified impact via an empty string (CVE-2016-7953).

Record
MGASA-2018-0011
Updated
2026-11-02
OSVUSN-3758-1 No score

libx11 vulnerabilities

Tobias Stoeckmann discovered that libx11 incorrectly handled certain images. An attacker could possibly use this issue to access sensitive information (CVE-2016-7942)

Tobias Stoeckmann discovered that libx11 incorrectly handled certain inputs. An attacker could possibly use this issue to access sensitive information. (CVE-2016-7943)

It was discovered that libx11 incorrectly handled certain inputs. An attacker could possibly use this issue to cause a denial of service. (CVE-2018-14598, CVE-2018-14599, CVE-2018-14600)

Record
USN-3758-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
libx11
Alpine:v3.2
before 1.6.3-r1
1.6.3-r1
libx11
Alpine:v3.3
before 1.6.3-r3
1.6.3-r3
libx11
Debian:12
before 2:1.6.4-1
2:1.6.4-1
libx11
Debian:13
before 2:1.6.4-1
2:1.6.4-1
libx11
Debian:14
before 2:1.6.4-1
2:1.6.4-1
libx11
Debian:7
before 2:1.5.0-1+deb7u3, plus listed versions
2:1.5.0-12:1.5.0-1+deb7u12:1.5.0-1+deb7u2
2:1.5.0-1+deb7u3
libx11
Mageia:5
before 1.6.5-1.mga5
1.6.5-1.mga5
libxv
Mageia:5
before 1.0.11-1.mga5
1.0.11-1.mga5
libxrender
Mageia:5
before 0.9.10-1.mga5
0.9.10-1.mga5
libxtst
Mageia:5
before 1.2.3-1.mga5
1.2.3-1.mga5
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Affected packages
PackageAffectedFixed
libxi
Mageia:5
before 1.7.7-1.mga5
1.7.7-1.mga5
libxrandr
Mageia:5
before 1.4.2-4.1.mga5
1.4.2-4.1.mga5
libxfixes
Mageia:5
before 5.0.3-1.mga5
5.0.3-1.mga5
libxvmc
Mageia:5
before 1.0.10-1.mga5
1.0.10-1.mga5
libx11
Ubuntu:14.04:LTS
before 2:1.6.2-1ubuntu2.1, plus listed versions
2:1.6.1-1ubuntu12:1.6.1-1ubuntu22:1.6.2-1ubuntu12:1.6.2-1ubuntu2
2:1.6.2-1ubuntu2.1
libx11
Ubuntu:16.04:LTS
before 2:1.6.3-1ubuntu2.1, plus listed versions
2:1.6.3-1ubuntu2
2:1.6.3-1ubuntu2.1
libx11
Ubuntu:18.04:LTS
before 2:1.6.4-3ubuntu0.1, plus listed versions
2:1.6.4-3
2:1.6.4-3ubuntu0.1

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2016-7943 is a critical vulnerability (CVSS 9.8) in X.org Libx11, published October 27, 2016. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 4.46%, the 91st percentile. Fixed in libx11 1.6.3-r1.

References

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