curl/docs/DEPRECATE.md
Viktor Szakats 89043ba906
cmake: drop support for CMake 3.17 and older
Require CMake 3.18 (2020-07-15) or newer, up from 3.7 (2016-11-11)
prior to this patch.

This requirement also applies to the distributed `curl-config.cmake`.

To allow dropping compatibility code maintained for old versions, and to
use features which were unpractical in separate code paths. Also to make
testing, documentation and development easier, CI builds faster due to
CMake performance improvements over time. (e.g. integration tests on
macOS run 8x faster (10 minutes is now under 1.5m) in CI, 2.5x faster on
Windows.)

CMake offers pre-built binaries for major platforms. They work without
an install step, just by unpacking and pointing the cmake command to
them. Making upgrades easy in many cases:
https://cmake.org/download/
https://cmake.org/files/
https://github.com/Kitware/CMake/releases

CMake 3.18 brings these feature as generally available when building or
consuming curl/libcurl:

LTO support, improved performance, `pkg-config` and interface target
support, `OBJECT` target (for faster libcurl builds), modern invocation
with `-S`/`-B` options, better support for custom linker options,
FetchContent, `GnuTLS::GnuTLS` target, `--verbose` and `--install`
options, `CMAKE_GENERATOR` env, last but not least unity mode and Ninja
generator.

For maximum build speed, use:
`-DCMAKE_UNITY_BUILD=ON -DCURL_DROP_UNUSED=ON`

As for deprecations, C++11 is required to build CMake itself, which may
be a limit on some platforms. autotools continues to cover them.

Follow-up to 9bcdfb3809 #20408
Follow-up to a7c974e038 #19902
Follow-up to dfbe035c8b #10161
Discussion: https://github.com/curl/curl/discussions/18704

Closes #20407
2026-03-21 13:24:47 +01:00

2.3 KiB

Items to be removed from future curl releases

If any of these deprecated features is a cause for concern for you, please email the curl-library mailing list as soon as possible and explain to us why this is a problem for you and how your use case cannot be satisfied properly using a workaround.

c-ares 1.16.0

In March 2026, we drop support for all c-ares versions before 1.16.0.

RTMP

RTMP in curl is powered by the 3rd party library librtmp.

  • RTMP is barely used by curl users (2.2% in the 2025 survey)
  • librtmp has no test cases, makes no proper releases and has not had a single commit within the last year
  • librtmp parses the URL itself and requires non-compliant URLs for this
  • we have no RTMP tests

Support for RTMP in libcurl gets removed in April 2026.

TLS-SRP Authentication

Transport Layer Security Secure Remote Password is a TLS feature that does not work with TLS 1.3 or QUIC and is virtually unused by curl users and in general.

TLS-SRP support gets removed in August 2026.

SMB goes opt-in

The SMB protocol has weak security and is rarely used these days. After curl 8.19.0 SMB support becomes opt-in.

NTLM goes opt-in

The NTLM authentication method has weak security and is rarely used these days. It has been deprecated by Microsoft and does not work over HTTP/2 or HTTP/3.

After curl 8.19.0 NTLM support becomes opt-in.

Past removals

  • axTLS (removed in 7.63.0)
  • Pipelining (removed in 7.65.0)
  • PolarSSL (removed in 7.69.0)
  • NPN (removed in 7.86.0)
  • Support for systems without 64-bit data types (removed in 8.0.0)
  • NSS (removed in 8.3.0)
  • gskit (removed in 8.3.0)
  • MinGW v1 (removed in 8.4.0)
  • NTLM_WB (removed in 8.8.0)
  • space-separated NOPROXY patterns (removed in 8.9.0)
  • hyper (removed in 8.12.0)
  • Support for Visual Studio 2005 and older (removed in 8.13.0)
  • Secure Transport (removed in 8.15.0)
  • BearSSL (removed in 8.15.0)
  • msh3 (removed in 8.16.0)
  • winbuild build system (removed in 8.17.0)
  • Windows CE (removed in 8.18.0)
  • Support for Visual Studio 2008 (removed in 8.18.0)
  • OpenSSL 1.1.1 and older (removed in 8.18.0)
  • Support for Windows XP (removed in 8.19.0)
  • OpenSSL-QUIC (removed in 8.19.0)
  • CMake 3.17 and older (removed in 8.21.0)