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CVE Record

CVE-2018-20340: Yubico libu2f-host 1.1.6 contains unchecked buffers in devs.c, which could enable a malicious token to expl...

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2018-20340 is a buffer overflow risk in Yubico libu2f-host 1.1.6. A malicious USB device pretending to be a security token could target a computer using the affected library. The source states genuine YubiKeys cannot perform this attack.

Executive priority

Treat this as a targeted endpoint exposure, not an internet-scale emergency. Prioritize regulated workstations, administrator machines, and shared environments where unknown USB devices may be introduced.

Technical view

The issue is described as unchecked buffers in devs.c in libu2f-host 1.1.6. The reported impact is a buffer overflow that could be used to attempt malicious code execution via a crafted USB device masquerading as a U2F token.

Likely exposure

Exposure is most likely on systems that still include libu2f-host 1.1.6 and accept security-token USB devices. The bundle does not identify broader affected versions, CPEs, or a CVSS score.

Exploitation context

No active exploitation is supported by the provided sources, and the CVE is not listed as KEV. The described scenario requires a crafted physical USB device and a host using the affected library.

Researcher notes

The prompt bundle lacks CVSS, CWE, CPE, and exact fixed-version details. Analysis should remain tied to libu2f-host 1.1.6 unless vendor or distro advisories confirm additional affected ranges.

Mitigation direction

  • Inventory systems for libu2f-host 1.1.6 or distro packages containing it.
  • Apply Yubico or distribution updates referenced by Debian and Gentoo advisories.
  • Remove libu2f-host where it is no longer needed.
  • Control use of untrusted USB security-token devices on managed endpoints.

Validation and detection

  • Check package manager records for installed libu2f-host versions.
  • Confirm affected systems received vendor or distribution security updates.
  • Review endpoint USB-device policy for unmanaged token-like devices.
  • Prioritize hosts where U2F tokens are used interactively.
Prepared
Confidence
medium
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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description · low confidence lookup

Credential and access behavior lookup

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cve · low confidence lookup

CVE-2018-20340 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
7Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.