CVE-2020-10185

The sync endpoint in YubiKey Validation Server before 2.40 allows remote attackers to replay an...

8.6 High

The sync endpoint in YubiKey Validation Server before 2.40 allows remote attackers to replay an OTP. NOTE: this issue is potentially relevant to persons outside Yubico who operate a self-hosted OTP validation service with a non-default configuration such as an open sync pool; the issue does NOT affect YubiCloud.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: Low
Integrity: Low
Availability: High

Exploit likelihood

1.68%Up 0.6 points since Apr 14, 2021

What each source reports

NVD Score used 8.6

Record: CVE-2020-10185
CVSS 3.1: 8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
CVSS 2.0: 6.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:P
Weakness: CWE-294
Updated: 2026-11-02

CVE List No score

Record: CVE-2020-10185
Updated: 2026-11-02

EUVDEUVD-2020-2647 No score

Record: EUVD-2020-2647
Updated: 2026-11-03

GitHub AdvisoriesGHSA-xcc3-mxq7-rg5h No score

The sync endpoint in YubiKey Validation Server before 2.40 allows remote attackers to replay an...

Record: GHSA-xcc3-mxq7-rg5h
Updated: 2026-11-02

OSV 8.6

Record: CVE-2020-10185
CVSS 3.1: 8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
Updated: 2026-11-02

OSVUBUNTU-CVE-2020-10185 8.6

Record: UBUNTU-CVE-2020-10185
CVSS 3.1: 8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
Updated: 2026-11-02

Affected products

yubico yubikey one time password validation server

Affected packages

Affected packages
Package	Affected	Fixed
`yubikey-val` Debian:8 From an advisory covering 2 CVEs	before 2.27-1+deb8u1, plus listed versions 2.27-1	2.27-1+deb8u1
`yubikey-val` Ubuntu:16.04:LTS	All versions, plus listed versions 2.28-12.33-12.33-1ubuntu1	None known
`yubikey-val` Ubuntu:18.04:LTS	All versions, plus listed versions 2.38-2	None known

History

History
Recorded	Changed	Sources
Nov 6, 2026	affected, facts
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-10185 is a high vulnerability (CVSS 8.6) in Yubico Yubikey One Time Password Validation Server, published March 5, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.68%, the 77th percentile. No source names a fixed version.