OpenVPN is een robuuste en gemakkelijk in te stellen opensource vpn-daemon waarmee verschillende private netwerken aan elkaar geknoopt kunnen worden via een versleutelde tunnel over internet. Voor de beveiliging wordt gebruikgemaakt van de OpenSSL-library, waarmee alle encryptie, authenticatie en certificatie kunnen worden afgehandeld. Sinds versie 2.6.15 zijn de volgende veranderingen en verbeteringen doorgevoerd:
Overview of changes in 2.6.17
BugfixesSecurity hardening
- Windows/interactive service: fix erroneous exit on error that could be used by a local Windows users to achieve a local denial-of-service (CVE-2025-13751)
- Windows/interactive service: improve service pipe robustness against file access races (uuid) and access by unauthorized processes (ACL).
- Upgrade bundled build instruction (vcpkg and patch) for pkcs11-helper to 1.31, fixing a parser bug
Overview of changes in 2.6.16
Security fixes:Code maintenance / Compat changes
- CVE-2025-13086: Fix memcmp check for the hmac verification in the 3way handshake. This bug renders the HMAC based protection against state exhaustion on
receiving spoofed TLS handshake packets in the OpenVPN server inefficient.Documentation updates
- Adapt to new "encrypt-then-mac" cipher suites in OpenSSL 3.6.0 - these need special handling which we don't do, so the t_lpback self-test failed on them. Exclude from list of allowed ciphers, as there is no strong reason today to make OpenVPN use these.
- Fix various compile-time warnings
Bugfixes
- Fix outdated and non-HTTPS URLs throughout the tree (doxygen, warnings, manpage, ...)
- Fix memcmp check for the hmac verification in the 3way handshake. This bug renders the HMAC based protection against state exhaustion on receiving spoofed TLS handshake packets in the OpenVPN server inefficient. CVE: 2025-13086
- Fix invalid pointer creation in tls_pre_decrypt() - technically this is a memory over-read issue, in practice, the compilers optimize it away so no negative effects could be observed.
- Windows: in the interactive service, fix the "undo DNS config" handling.
- Windows: in the interactive service, disallow using of "stdin" for the config file, unless the caller is authorized OpenVPN Administrator
- Windows: in the interactive service, change all netsh calls to use interface index and not interface name - sidesteps all possible attack avenues with special characters in interface names.
- Windows: in the interactive service, improve error handling in some "unlikely to happen" paths.
- Auth plugin/script handling: properly check for errors in creation on $auth_failed_reason_file (arf).
- For incoming TCP connections, close-on-exec option was applied to the wrong socket fd, leaking socket FDs to child processes.
- sitnl: set close-on-exec flag on netlink socket
- ssl_mbedtls: fix missing perf_pop() call (optional performance profiling)
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