General Information
On 11th of November 2025 the following was released:
- ISL Pronto 4.4.2526.10 for Windows (release_date=2025-11-07, Build=f8140bbf0e957649d3773b2019b4c5fc8d0d50a1, platform=win32, os_version=0x06010000-0x7fffffff)
- ISL Pronto 4.4.2526.10 for Mac (release_date=2025-11-07, Build=f8140bbf0e957649d3773b2019b4c5fc8d0d50a1, platform=mac, os_version=0x0a0e00-0x1bffff)
- ISL Pronto 4.4.2526.10 for Linux64 (release_date=2025-11-07, Build=f8140bbf0e957649d3773b2019b4c5fc8d0d50a1, platform=linux64, os_version=0x030a000000021100-0xffffffffffffffff)
All updates have release date set to 2025-11-07. Your ESS will need to be same or higher to be able to update your server. This release is available to all countries except Japan.
Upgrading to new version
Hosted service users please check Upgrading Hosted Service.
Server license users please check Upgrading Server License.
Improvements
ISL Pronto - Desktop - Update SoundTouch library (SPECIAL) [ISLPRONTO-1409] More
Description
The SoundTouch libarary which is used for sound playback was updated to latest available version (2.4.0).
ISL Pronto - Desktop - Remove yubico2fhost binary (SPECIAL) [ISLPRONTO-1415] More
Description
Removed the obsolete binary file called yubico2fhost from ISL Pronto installation.
ISL Pronto - Desktop - Update Mbedtls to 2.28.10 (SECURITY) [ISLPRONTO-1401] More
Description
Internal mbedTLS library was updated to version 2.28.10.
ISL Pronto - Desktop - Add cmd line for extra step before connecting to ISL Light session (FEATURE) [ISLPRONTO-1256] More
Description
When starting a remote desktop session from within ISL Pronto application the client will now have to click on connect button once the downloaded application is run. In previous version of ISL Pronto the ISL Light Client application got connected immediately without additional connect click, but now this click is required.
ISL Pronto - Desktop - Parse IPv6 server address correctly (FEATURE) [ISLPRONTO-1325] More
Description
Server address setting in ISL Pronto connections will now correctly parse IPv6 formats like "::1" and "[::1]:7615" when connecting. IPv6 address will also be sent correctly to ICP as meta info.
ISL Pronto - Desktop - Add support for allowed extracted file names (FEATURE) [ISLPRONTO-1346] More
Description
Support for CRC32 checksum for extra file was added on Windows and it's now mandatory. In case the checksum is not correct it will spawn an error and prevent program from running. Additionally only the following extracted files are allowed in the unsigned part of the executable:
- branch.txt
- address.txt
- custom.txt
- debug_options.txt
ISL Pronto - Desktop - WinINet http proxy bypass and force_auth options (FEATURE) [ISLPRONTO-1393] More
Description
Two options were added to AutoTransport which affect wininet-http and wininet-https transports:
- http_proxy_bypass: configure which hostnames should (or not) use direct connection without proxy, use <-loopback> to allow localhost connections through proxy
- http_proxy_force_auth: immediately start with configured user+password when connecting, used to resolve a problem when Windows system account is not allowed to connect through proxy but http_proxy_user is allowed and proxy is using Windows integrated authentication
ISL Pronto - Desktop - AutoTransport add SNI to permissive SSL mode (FEATURE) [ISLPRONTO-1398] More
Description
AutoTransport methods wsstun-direct, wsstun-proxy, https-direct, https-proxy were fixed to use SNI (send connection hostname in SSL handshake) in order to improve compatibility with third party load balancers like Cloudflare.
ISL Pronto - Desktop - Add ecdh_ctx log key to mbedTLS log line (FEATURE) [ISLPRONTO-1404] More
Description
The log line of ISL Pronto now includes ecdh_ctx log key which shows which algorithm was used to establish the shared secret.
ISL Pronto - Desktop - Enable xz LZMA decoder (FEATURE) [ISLPRONTO-1407] More
Description
LZMADecode was removed from hefa-rpt and XZ is now included as a default in all builds of hefa-rpt.
ISL Pronto - Desktop - Update logo ISL Online powered by PDQ (FEATURE) [ISLPRONTO-1411] More
Description
Updated default ISL Pronto logo to include powered by PDQ.
ISL Pronto - Desktop - Reject simple 200 OK to avoid confusion with regular web servers (DEFECT) [ISLPRONTO-1386] More
Description
In previous version when initiating a connection with ISL Conference Proxy only the return status was checked ( status code 200 ) so the library was checking the same transport. Now in addition to the status code check the content of the returned data is also checked which will fail in case ISL Conference Proxy was not the one who replied and the library will continue to check other transports.
The defect was fixed.
ISL Pronto - Desktop - Crashes in timer callback (DEFECT) [ISLPRONTO-1387] More
Description
In some cases when using the chat timer functionality, it could happen that application crashed when the timeout callback was executed. Handling of callback was redesigned, application should not crash anymore.
The defect was fixed.
ISL Pronto - Desktop - Failed to get correct desktop folder on localized Linux (DEFECT) [ISLPRONTO-1388] More
Description
In case Linux users had a localized Linux setup the Desktop location is not present in /home/username/Desktop instead the last part is localized to the selected language during install. Checking for users desktop folder was redesigned, it will now query the Linux system to let it know the Desktop location instead of using the default Desktop value.
The defect was fixed.
ISL Pronto - Desktop - Fix HTTPS proxy for wsstun-proxy (DEFECT) [ISLPRONTO-1389] More
Description
In previous versions where users used wsstun-proxy it was using HTTP proxy instead of HTTPS proxy. The incorrect usage was changed, so with wsstun-proxy type of connection the HTTPS proxy is now used.
The defect was fixed.
ISL Pronto - Desktop - Fix PAC parser for multiple returned HTTP proxy addresses (DEFECT) [ISLPRONTO-1390] More
Description
In previous versions if users had multiple proxies defined in the PAC file in some cases the incorrect proxy was selected. PAC file parser was redesigned and now the correct proxy is used.
The defect was fixed.
ISL Pronto - Desktop - AutoTransport SSL protocol and ciphers setting (DEFECT) [ISLPRONTO-1391] More
Description
Options "ssl_protocol" and "ssl_ciphers" were added to AutoTransport. Besides legacy OpenSSL format, the options support numeric hex codes:
- ssl_protocol: "0x0301-0x10000" for TLS 1.0 profile and "0x0303-0x10000" for TLS 1.2 profile. 3-byte hex code "0x10000" is interpreted as no bound.
- ssl_ciphers: can now be specified using a simple numeric hex code list: "0x1302 0x1301 ..."
ISL Pronto - Desktop - Ensure closed sockets in autotransport - Windows, HTTP tunnels (DEFECT) [ISLPRONTO-1392] More
Description
HTTP tunnel (httpt-direct) was fixed not to produce many TCP connections with CLOSE_WAIT state, which is a resource leak (server closes the connection, but the client does not).
The defect was fixed.
ISL Pronto - Desktop - Exe details are showing incorrect version when downloading application using /download (DEFECT) [ISLPRONTO-1395] More
Description
On Windows main ISL Pronto executable was filled with incorrect information about version and other information. Populating meta data information was redesigned, correct information is now displayed.
The defect was fixed.
ISL Pronto - Desktop - Increase timeout on "watcher" watchdog thread (DEFECT) [ISLPRONTO-1396] More
Description
Watchdog implementation of Windows was updated with:
- updated timeouts
- added log for thread ids
- added NOX on failed thread create
- removed use of rand function that uses enter critical section
The time for unresponsive scheduler check is 2,5 min - before it was 2min. The time for unresponsive watcher check is now 10 min - before it was 2min. We now report also the wd count that was reached when watchdog crashed.
ISL Pronto - Desktop - Always enable TLS when opening AT MUX channel (DEFECT) [ISLPRONTO-1399] More
Description
In previous version some mux connection channels were not protected by TLS session. TLS session is now enabled on all mux channels.
The defect was fixed.
ISL Pronto - Desktop - Fix icon copy in secure part (DEFECT) [ISLPRONTO-1400] More
Description
On macOS in some cases the application icons were not copied in a secure manner. Copying of application icons was redesigned, so they are now copied securely.
The defect was fixed.
ISL Pronto - Desktop - Change dots to underscores for filename on Linux (DEFECT) [ISLPRONTO-1405] More
Description
In previous versions the filename version was delimited with dots. This caused an issue when build number was less then 10 as the application opened as text editor. The dots were now replaced with underscores and this now always executes the application correctly.
The defect was fixed.
ISL Pronto - Desktop - Incorrect exe information (DEFECT) [ISLPRONTO-1406] More
Description
Some additional executables used by ISL Pronto were found that did not have correct version shown in the details tab. Executables are now showing the correct versions.
The defect was fixed.
ISL Pronto - Desktop - Exe details are showing incorrect version (DEFECT) [ISLPRONTO-1410] More
Description
ISL Pronto was showing incorrect version when checking properties of the install and some other executable files. The correct version is now written.
The defect was fixed.
ISL Pronto - Desktop - Use short explicit hex code SSL cipher suites (DEFECT) [ISLPRONTO-1412] More
Description
MbedTLS cipher suite used was simplified to be similar to server OpenSSL cipher suite. Additionally the following ciphers were removed:
- DHE
- ECDH
- CAMELLIA
- 3DES (except TLS-RSA-WITH-3DES-EDE-CBC-SHA)
ISL Pronto - Desktop - Adjust launch to support options '8' on macOS correctly (DEFECT) [ISLPRONTO-1413] More
Description
On macOS the resources could be injected to be copied by launcher to the destination folder. That was due to this operation being appended in the unsigned part of the package. The copy operation must now first be allowed in the signed part of the package in order to be executed in the unsigned part.
The defect was fixed.
ISL Pronto - Desktop - Application name is not resolved correctly in installer (DEFECT) [ISLPRONTO-1416] More
Description
On Linux when installing ISL Pronto application the dialog which is spawned had incorrect title. Instead of either default ISL Pronto and version or customized name of the installer it was showing the name of the internal variable. Displaying of the title was redesigned and it's now shown correctly.
The defect was fixed.