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OpenVPN CVE-2026-40215

| EUVDEUVD-2026-35200 MEDIUM
Out-of-bounds Read (CWE-125)
2026-04-22
Information Disclosure Buffer Overflow Suse
6.1
CVSS 4.0 · NVD
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Severity by source

NVD PRIMARY
6.1 MEDIUM
CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:N/VA:H/SC:L/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
SUSE
6.8 MEDIUM
AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H

Primary rating from NVD.

CVSS VectorNVD

CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:N/VA:H/SC:L/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

5
Source Code Evidence Fetched
Jun 08, 2026 - 21:24 vuln.today
Analysis Generated
Jun 08, 2026 - 21:24 vuln.today
CVSS changed
Jun 08, 2026 - 21:22 NVD
6.1 (MEDIUM)
Patch released
Apr 24, 2026 - 12:21 nvd
Patch available
CVE Published
Apr 22, 2026 - 19:46 nvd
N/A

Description PRE-NVD

Disclosed via GitHub release of openvpn/openvpn. NVD scoring and full description are pending.

AnalysisAI

OpenVPN's TLS handshake race condition exposes confidential packet data from prior handshake sessions to authenticated remote attackers, affecting versions before 2.6.20 in the 2.6.x branch and before 2.7.2 in the 2.7.x branch. The CWE-125 out-of-bounds read flaw scores 6.1 under CVSS 4.0 with High confidentiality and availability impacts, though the AC:H (High Complexity) rating reflects that successful exploitation requires winning a narrow timing window, limiting opportunistic mass exploitation. No public exploit code has been identified at time of analysis and this CVE is not listed in CISA KEV; vendor-released patches for both stable branches were published April 22, 2026.

Technical ContextAI

OpenVPN is a widely-deployed open-source VPN solution that uses TLS for its control channel, managing session establishment and renegotiation through a TLS state machine. The root cause class is CWE-125 (Out-of-bounds Read): a race condition in the handshake logic creates a time-of-check-to-time-of-use window where shared handshake state can be accessed without adequate synchronization. When the race is won, memory belonging to a previous handshake context is read out-of-bounds and can be included in packet data transmitted to the current session, constituting an information disclosure. The 'Buffer Overflow' tag in the source data appears to be a tagging imprecision - CWE-125 is a read-side flaw, not a write overflow. The CVSS 4.0 vector (AV:N/AC:H/AT:N/PR:L/UI:N) confirms network reachability with high complexity and low-privilege authentication required, consistent with a race condition exploitable only by an established, authenticated VPN peer. This vulnerability is distinct from CVE-2026-35058, a server ASSERT crash via malformed tls-crypt-v2 packets that was fixed in the same v2.6.20 and v2.7.2 releases.

RemediationAI

Upgrade to OpenVPN 2.6.20 or OpenVPN 2.7.2, both released April 22, 2026, which contain the direct fix for this race condition. Binaries and source are available at https://github.com/OpenVPN/openvpn/releases/tag/v2.6.20 and via the OpenVPN Community Downloads page for Windows MSI installers. Linux package users should follow their distribution's advisory; Ubuntu users should apply the update referenced in USN-8286-1 (https://ubuntu.com/security/notices/USN-8286-1) and consult community Linux package repos per the OpenVPN wiki. If immediate patching is not feasible, restrict which clients are permitted to initiate TLS renegotiation by reviewing server-side renegotiation configuration (--renegotiate-seconds and --reneg-bytes options), though disabling renegotiation entirely may impact long-lived sessions and has the trade-off of keeping TLS sessions alive with older key material. Additionally, narrowing the authenticated client pool - by auditing certificate issuance and revoking certificates for untrusted clients - reduces the PR:L attack surface, since only authenticated peers can trigger the race. These compensating controls do not eliminate the vulnerability and patching remains the only confirmed remediation.

Same weakness CWE-125 – Out-of-bounds Read

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Module for Basesystem 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected
SUSE Linux Enterprise Server 16.0 Affected

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CVE-2026-40215 vulnerability details – vuln.today
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