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CVE-2018-20340· NVD / CVE Program· CNA mitre

Yubico libu2f-host 1.1.6 contains unchecked buffers in devs.c, which could enable a malicious token to exploit a buffer overflow.

Noroxi assessment

Priority: Monitor (action score 27/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.49% (FIRST EPSS).
  • Physical access to the device is required. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: libu2f-host (Debian:12) 1.1.7-1; libu2f-host (Debian:9) 1.1.2-2+deb9u1; libu2f-host (openSUSE:Leap 15.0) 1.1.6-lp151.2.3.1.

Low priority for now. Upgrade to libu2f-host (Debian:12) 1.1.7-1; libu2f-host (Debian:9) 1.1.2-2+deb9u1; libu2f-host (openSUSE:Leap 15.0) 1.1.6-lp151.2.3.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

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.

MediumCVSS 6.8 · v3.0—No exploit Fix available
Published
Mar 21, 2019
Updated
Jun 16, 2026
EPSS
0.5% · 41th percentile

Report tools

JSON

Action score

27

Monitor

Low priority for now.

CVSS
27 / 40 · 6.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
yubicolibu2f-host
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux9.0
  • yubico libu2f-host1.1.6

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12libu2f-hostbefore 1.1.7-11.1.7-1
Debian:9libu2f-hostbefore 1.1.2-2+deb9u11.1.2-2+deb9u1
openSUSE:Leap 15.0libu2f-hostbefore 1.1.6-lp151.2.3.11.1.6-lp151.2.3.1
openSUSE:Leap 15.2libu2f-hostbefore 1.1.10-lp152.4.3.11.1.10-lp152.4.3.1
openSUSE:Leap 15.3libu2f-hostbefore 1.1.10-3.9.11.1.10-3.9.1
SUSE:Linux Enterprise Desktop 12 SP4libu2f-hostbefore 1.1.6-3.5.11.1.6-3.5.1
SUSE:Linux Enterprise Desktop 12 SP4pam_u2fbefore 1.0.8-3.3.11.0.8-3.3.1
SUSE:Linux Enterprise Module for Basesystem 15libu2f-hostbefore 1.1.6-3.3.31.1.6-3.3.3
SUSE:Linux Enterprise Module for Basesystem 15 SP2libu2f-hostbefore 1.1.10-3.9.11.1.10-3.9.1

Same product

yubico: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-9578In devs.c in Yubico libu2f-host before 1.1.8, the response to init is misparsed, leaking uninitialized stack memory back to the device.
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:libu2f-host1.1.7-1 · Debian:12Package registry (OSV)
opensuse:libu2f-host1.1.6-lp151.2.3.1 · openSUSE:Leap 15.0Package registry (OSV)
suse:libu2f-host1.1.6-3.3.3 · SUSE:Linux Enterprise Module for Basesystem 15Package registry (OSV)
suse:pam_u2f1.0.8-3.3.1 · SUSE:Linux Enterprise Desktop 12 SP4Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Physical access to the device is required.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Physical
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer

CVSS vector

CVSS:3.0/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records