Description
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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 8 | yubikey-val | 2.27-1+deb8u1 | DLA-2141-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | yubikey-val | No fix yet | — |
| Ubuntu 16.04 LTS | yubikey-val | No fix yet | — |
Advisories 1
- DLA-2141-1 yubikey-val - security update Debian Security (DSA / DLA) · Mar 9, 2026