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VulnerabilityPublished

CVE-2026-40947: Yubico libfido2 · Untrusted Search Path

Affects Yubico libfido2Source CVE Database V5

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Not known to be exploited · CVSS 2.9 Low : upgrade to 1.17.0 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
2.9Low
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.17.0, 2.2.0, 5.9.1
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade libfido2 to 1.17.0; python-fido2 to 2.2.0; yubikey-manager to 5.9.1.

Affected software

ProductAffectedFixed in
Yubicolibfido2Affected
  • <1.17.0
Fixed in
  • 1.17.0
Yubicopython-fido2Affected
  • <2.2.0
Fixed in
  • 2.2.0
Yubicoyubikey-managerAffected
  • <5.9.1
Fixed in
  • 5.9.1
PyPIpython-fido2pkg:pypi/python-fido2Other threatsAffected
  • <2.2.0
Fixed in
  • 2.2.0
PyPIyubikey-managerpkg:pypi/yubikey-managerOther threatsAffected
  • <5.9.1
Fixed in
  • 5.9.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, restrict local access to trusted users and environments to reduce risk. Monitor for vendor updates regarding patches or official mitigations.

Description

Yubico libfido2 before 1.17.0, python-fido2 before 2.2.0, and yubikey-manager before 5.9.1 have an unintended DLL search path.

References

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