OpenVPN 2.5.1 and earlier versions allows a remote attackers to bypass authentication and access control channel data on servers configured with deferred authentication, which can be used to potentially trigger further information leaks.
An official patch is available. Apply the patch as soon as possible.
CVSS v4.0 Metrics
Exploitability
Attack VectorNetwork
ComplexityLow
RequirementsPresent
PrivilegesNone
User InteractionNone
Threat
Exploit MaturityPoC
Vulnerable System
ConfidentialityHigh
IntegrityNone
AvailabilityNone
Subsequent System
ConfidentialityNone
IntegrityNone
AvailabilityNone
Supplemental
SafetyNegligible
AutomatableYes
RecoveryAutomatic
Value DensityConcentrated
UrgencyMedium
Patch StatusOfficial Patch
Change Log
| Date | Source | Changes | Score |
|---|
| 2026-07-21 | PoC | E: U→P | 4.6 → 6.9 |
| 2026-07-21 | nvd | AV: P→N, AC: H→L, PR: H→N, UI: A→N, VC: N→H | 0.0 → 4.6 |
| 2026-07-21 | nvd | patch: Unavailable→Official Patch | 0.0 → 0.0 |
| 2026-07-21 | cve.org | initial, patch: Unavailable | 0.0 |
Affected Software
| Vendor | Product | Version |
|---|
| canonical | ubuntu_linux | 18.04 |
| canonical | ubuntu_linux | 20.04 |
| canonical | ubuntu_linux | 20.10 |
| canonical | ubuntu_linux | 21.04 |
| debian | debian_linux | 9.0 |
| fedoraproject | fedora | 32 |
| fedoraproject | fedora | 33 |
| fedoraproject | fedora | 34 |
| n/a | OpenVPN | ≤ 2.5.1 versions |
| openvpn | openvpn | < 2.4.11 |
| openvpn | openvpn | ≥ 2.5.0, < 2.5.2 |
Published: 2021-04-26
