CVE-2018-16738 [Low] | Authentication Bypass in Tinc

CVE-2018-16738 is rated Low Risk (39.7/100): CVSS Low severity, with medium exploitation likelihood (EPSS 1.35%). EPSS rose +1.13% over the last day, indicating growing attacker interest. Monitor for updates and reassess as exploit intelligence or EPSS changes.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.22%	1.35%	+1.13%
2	2026-05-27	0.33%	0.22%	-0.10%
3	2025-10-12	—	0.33%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.22%

1.35%

+1.13%

2026-05-27

0.33%

0.22%

-0.10%

2025-10-12

—

0.33%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
3.7	3.1	LOW	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N` 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:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. 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:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	2.2	1.4	[email protected]
4.3	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:N/I:P/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:N) No availability impact.	8.6	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

3.7

3.1

LOW

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N 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:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N): Service keeps running; no real outage angle.

2.2

1.4

[email protected]

4.3

2.0

MEDIUM

AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:M): Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:N): No availability impact.

8.6

2.9

[email protected]

OS Trackers for CVE-2018-16738

vendor	priority	summary	link
`alpine`	low	CVE-2018-16738: 1 source package rows (tinc); 10 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 10, open 0.	https://security.alpinelinux.org/vuln/CVE-2018-16738
`debian`	not yet assigned	CVE-2018-16738 not yet assigned priority: Debian including 1 source packages (tinc), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2018-16738
`ubuntu`	medium	CVE-2018-16738 medium priority: Ubuntu including 1 source packages (tinc), 19 status rows across 19 suites (bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 14, needed 2, DNE 1, ignored 1, released 1.	https://ubuntu.com/security/CVE-2018-16738

Affected software / configurations for CVE-2018-16738

Vendor	Product	Version	Raw CPE
tinc-vpn	tinc	>= 1.0.30, <= 1.0.34	cpe:2.3:a:tinc-vpn:tinc::::::::
debian	debian_linux	9.0	cpe:2.3:o:debian:debian_linux:9.0:::::::*
starwindsoftware	starwind_virtual_san	v8	cpe:2.3:a:starwindsoftware:starwind_virtual_san:v8:build12533::::vsphere::*
starwindsoftware	starwind_virtual_san	v8	cpe:2.3:a:starwindsoftware:starwind_virtual_san:v8:build12658::::vsphere::*

References for CVE-2018-16738

URL	Tags
http://tinc-vpn.org/security/	Vendor Advisory
http://www.tinc-vpn.org/git/browse?p=tinc%3Ba=commit%3Bh=d3297fbd3b8c8c8a4661f5bbf89aca5cacba8b5a
https://www.debian.org/security/2018/dsa-4312	Third Party Advisory
https://www.starwindsoftware.com/security/sw-20190227-0002/	Third Party Advisory

URL

CVE-2018-16738

Exploit prediction scoring system (EPSS) score for CVE-2018-16738

Common vulnerability scoring system (CVSS) metrics for CVE-2018-16738

Weakness enumeration for CVE-2018-16738

OS Trackers for CVE-2018-16738

Affected software / configurations for CVE-2018-16738

References for CVE-2018-16738