CVE-2016-6866

slock allows attackers to bypass the screen lock via vectors involving an invalid password hash,...

7.5 HighFix available

slock allows attackers to bypass the screen lock via vectors involving an invalid password hash, which triggers a NULL pointer dereference and crash.

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: None
Integrity: None
Availability: High

Exploit likelihood

2.89%Up 1.8 points since Feb 4, 2022

What each source reports

NVD Score used 7.5

slock allows attackers to bypass the screen lock via vectors involving an invalid password hash, which triggers a NULL pointer dereference and crash.

Record: CVE-2016-6866
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0: 5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness: CWE-476
Updated: 2026-11-02

CVE List No score

slock allows attackers to bypass the screen lock via vectors involving an invalid password hash, which triggers a NULL pointer dereference and crash.

Record: CVE-2016-6866
Updated: 2026-11-02

EUVDEUVD-2016-7751 No score

slock allows attackers to bypass the screen lock via vectors involving an invalid password hash, which triggers a NULL pointer dereference and crash.

Record: EUVD-2016-7751
Updated: 2026-11-03

GitHub AdvisoriesGHSA-h53p-2gg5-7vfm 7.5

slock allows attackers to bypass the screen lock via vectors involving an invalid password hash,...

slock allows attackers to bypass the screen lock via vectors involving an invalid password hash, which triggers a NULL pointer dereference and crash.

Record: GHSA-h53p-2gg5-7vfm
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-476
Updated: 2026-11-02

OSV 7.5

slock allows attackers to bypass the screen lock via vectors involving an invalid password hash, which triggers a NULL pointer dereference and crash.

Record: CVE-2016-6866
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2016-6866 7.5

slock allows attackers to bypass the screen lock via vectors involving an invalid password hash, which triggers a NULL pointer dereference and crash.

Record: DEBIAN-CVE-2016-6866
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVUBUNTU-CVE-2016-6866 7.5

slock allows attackers to bypass the screen lock via vectors involving an invalid password hash, which triggers a NULL pointer dereference and crash.

Record: UBUNTU-CVE-2016-6866
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVMGASA-2016-0308 No score

Updated slock packages fix security vulnerability

The slock utility is susceptible to crash when verifying a password for a user without a valid shadow hash entry (CVE-2016-6866).

Record: MGASA-2016-0308
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`suckless-tools` Debian:12	before 41-1	41-1
`suckless-tools` Debian:13	before 41-1	41-1
`suckless-tools` Debian:14	before 41-1	41-1
`suckless-tools` Debian:7	before 38-2+deb7u1, plus listed versions 38-2	38-2+deb7u1
`slock` Mageia:5	before 1.1-5.1.mga5	1.1-5.1.mga5
`suckless-tools` Ubuntu:14.04:LTS	before 40-1+deb8u2build0.14.04.1, plus listed versions 38-240-1	40-1+deb8u2build0.14.04.1

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

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

In short

CVE-2016-6866 is a high vulnerability (CVSS 7.5) in Suckless Slock, published August 20, 2016. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.89%, the 86th percentile. Fixed in suckless-tools 41-1.

References

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