HOMEVULNERABILITIESCVE-2018-20340
MEDIUM

CVE-2018-20340

CWE-119Published: March 21, 2019· Updated: Jun 17, 2026

6.8
CVSS v3.1

Official Description

Yubico libu2f-host 1.1.6 contains unchecked buffers in devs.c, which could enable a malicious token to exploit a buffer overflow. An attacker could use this to attempt to execute malicious code using a crafted USB device masquerading as a security token on a computer where the affected library is currently in use. It is not possible to perform this attack with a genuine YubiKey.

NVD Source

Technical Analysis

CVE-2018-20340 requires local access, meaning attackers must already have a foothold on the target system.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 6.8.

From a weakness classification perspective (CWE-119): Buffer overflow vulnerabilities can lead to arbitrary code execution or denial of service by corrupting adjacent memory.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorPhysical
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.0/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

Debian1 product(s)
debian linux
yubico1 product(s)
libu2f-host
Source: NVD CPE · 2 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://www.yubico.com/support/security-advisories/ysa-2019-01/
PATCHhttps://www.yubico.com/support/security-advisories/ysa-2019-01/
ADVISORYhttps://developers.yubico.com/libu2f-host/Release_Notes.html
ADVISORYhttps://seclists.org/bugtraq/2019/Feb/23
ADVISORYhttps://www.debian.org/security/2019/dsa-4389
ADVISORYhttps://developers.yubico.com/libu2f-host/Release_Notes.html
ADVISORYhttps://seclists.org/bugtraq/2019/Feb/23
ADVISORYhttps://www.debian.org/security/2019/dsa-4389

All References (12)

→
https://blog.inhq.net/posts/yubico-libu2f-host-vuln-part1/
→
https://developers.yubico.com/libu2f-host/Release_Notes.htmlRelease Notes · Vendor Advisory
→
https://seclists.org/bugtraq/2019/Feb/23Mailing List · Third Party Advisory
→
https://security.gentoo.org/glsa/202004-15
→
https://www.debian.org/security/2019/dsa-4389Third Party Advisory
→
https://www.yubico.com/support/security-advisories/ysa-2019-01/Patch · Vendor Advisory
→
https://blog.inhq.net/posts/yubico-libu2f-host-vuln-part1/
→
https://developers.yubico.com/libu2f-host/Release_Notes.htmlRelease Notes · Vendor Advisory
→
https://seclists.org/bugtraq/2019/Feb/23Mailing List · Third Party Advisory
→
https://security.gentoo.org/glsa/202004-15
→
https://www.debian.org/security/2019/dsa-4389Third Party Advisory
→
https://www.yubico.com/support/security-advisories/ysa-2019-01/Patch · Vendor Advisory

Quick Facts

CVE IDCVE-2018-20340
CVSS Score6.8 / 10
SeverityMEDIUM
WeaknessCWE-119
CISA KEVNo
Affected2 vendor(s)
PublishedMar 21, 2019

Related CVEs (CWE-119)

CVE-2012-5965
10.0
CVE-2012-5963
10.0
CVE-2008-4556
10.0
CVE-2002-2251
10.0
CVE-2012-5964
10.0
CVE-2012-5962
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2018-20340 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
← All Vulnerabilities·Search for CVE-2018-20340·NVD