Detections
Analytics
FreeBSD : OpenVPN -- HMAC verification on source IP address ineffective (17a40d76-c3fd-11f0-b513-0da7be77c170)
medium Nessus Plugin ID 275731
Language:
Synopsis
The remote FreeBSD host is missing one or more security-related updates.Description
The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the 17a40d76-c3fd-11f0-b513-0da7be77c170 advisory.Arne Schwabe reports:
Fix memcmp check for the hmac verification in the 3way handshake being inverted This is a stupid mistake but causes all hmac cookies to be accepted, thus breaking source IP address validation. As a consequence, TLS sessions can be openend and state can be consumed in the server from IP addresses that did not initiate an initial connection.
While at it, fix check to only allow [t-2;t] timeslots, disallowing HMACs coming in from a future timeslot.
Tenable has extracted the preceding description block directly from the FreeBSD security advisory.
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.
Solution
Update the affected packages.See Also
Plugin Details
Severity: Medium
ID: 275731
File Name: freebsd_pkg_17a40d76c3fd11f0b5130da7be77c170.nasl
Version: 1.2
Type: local
Family: FreeBSD Local Security Checks
Published: 11/18/2025
Updated: 12/12/2025
Supported Sensors: Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 4.4
CVSS v2
Risk Factor: Medium
Base Score: 6.4
Temporal Score: 4.7
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N
CVSS Score Source: CVE-2025-13086
Vulnerability Information
CPE: p-cpe:/a:freebsd:freebsd:openvpn-devel, p-cpe:/a:freebsd:freebsd:openvpn, cpe:/o:freebsd:freebsd
Required KB Items: Host/local_checks_enabled, Host/FreeBSD/release, Host/FreeBSD/pkg_info
Exploit Ease: No known exploits are available
Patch Publication Date: 11/17/2025
Vulnerability Publication Date: 11/17/2025
Reference Information
CVE: CVE-2025-13086
IAVA: 2025-A-0896