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Fencer Vulns
low 3.7

CVE-2020-11810 json

An issue was discovered in OpenVPN 2.4.x before 2.4.9.

published 2020-04-27 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-4152

cvss
3.7
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.7%
EPSS 1.7% chance of exploitation in 30 days, percentile 76%
public exploits
0
none known

Summary

An issue was discovered in OpenVPN 2.4.x before 2.4.9. An attacker can inject a data channel v2 (P_DATA_V2) packet using a victim's peer-id. Normally such packets are dropped, but if this packet arrives before the data channel crypto parameters have been initialized, the victim's connection will be dropped. This requires careful timing due to the small time window (usually within a few seconds) between the victim client connection starting and the server PUSH_REPLY response back to the client. This attack will only work if Negotiable Cipher Parameters (NCP) is in use.

Patch / fix

  • openvpn openvpn 2.4.9
  • openvpn Debian 14, Debian 13, Debian 12 2.4.9-1

debian advisories DEBIAN-CVE-2020-11810

  • openvpn Ubuntu 18.04 LTS 2.4.4-2ubuntu1.5
  • openvpn Ubuntu 20.04 LTS 2.4.7-1ubuntu2.20.04.2

ubuntu advisories UBUNTU-CVE-2020-11810

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • openvpn SLE Module for Basesystem 15 SP3, SLE Module for Basesystem 15 SP2 2.4.3-5.7.1

suse advisories SUSE-SU-2021:1577-1

  • openvpn openSUSE Tumbleweed 2.5.3-1.2
  • openvpn openSUSE Leap 15.2 2.4.3-lp152.6.3.1

opensuse advisories openSUSE-SU-2024:11128-1openSUSE-SU-2021:0734-1

  • openvpn Alpine 3.24, Alpine 3.23, Alpine 3.22 +12 more 2.4.9-r0

alpine advisories ALPINE-CVE-2020-11810

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • openvpn Arch Linux 2.4.9-1

arch linux advisories AVG-1135

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-11810 updated cvss 3.7

openvpn: race condition between allocating peer-id and initializing data channel key

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.65% chance of exploitation in the next 30 days, higher than 76% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • community.openvpn.net https://community.openvpn.net/openvpn/ticket/1272 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.