CVE-2026-84732Network attack vector

Service interruption via unbounded ACK retransmission timeout

Published Sep 7, 2026 · Updated Sep 8, 2026

Integer overflow in OpenVPN 2.6 releases through 2.6.22 and 2.7 releases through 2.7.6 allows remote attackers to interrupt VPN service. The reliability layer doubles retransmission timeouts without a bound and accepts out-of-window packet IDs as acknowledgements, letting crafted ACKs manipulate send-buffer retransmission state until the timeout overflows. No authentication or user interaction is required; the bounded consequence is an unresponsive control channel and interrupted VPN availability.

CVSS severity8.7
High
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in OpenVPN 2.6 releases through 2.6.22 and 2.7 releases through 2.7.6 allows remote attackers to interrupt VPN service. The reliability layer doubles retransmission timeouts without a bound and accepts out-of-window packet IDs as acknowledgements, letting crafted ACKs manipulate send-buffer retransmission state until the timeout overflows. No authentication or user interaction is required; the bounded consequence is an unresponsive control channel and interrupted VPN availability.

The record

CVE
CVE-2026-84732
Published
Sep 7, 2026
Updated
Sep 8, 2026
Vendor
OpenVPN Inc.
Product
OpenVPN
Classifications
CWE-190, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=2.6.22
  2. Affected versionversion=0 <=2.7.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenVPN Inc. · OpenVPNversion=0 <=2.6.22; version=0 <=2.7.6

Published CVSS scores

5.3Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
8.7OpenVPN CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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